There is also the problem, that some OEMs add their own "battery optimizations". If you simply don't run anything its indeed very battery efficient... Forcing push notifications through some central service has minimal benefits at best. Open source variants are forced to publish annoying persistent notifications and ask the user to flip some "battery optimization" toggle deep inside the settings to not get killed, of course this often enough changes with Android versions.

You're talking about the standard battery optimizations where the end user needs to approve apps repeatedly waking up the app from sleep and running continuously while awake. OEMs have been required to stop doing most of the non-standard things they were doing in relation to this and it's not hard for app developers to deal with anymore unless they care about it on end-of-life Android versions.

The persistent notification for foreground services is mandatory for apps to implement but entirely optional for users. The notification channel can simply be toggled off to hide it. Apps are required to make a notification for each foreground service to provide transparency. It gives apps a way to explain why they're doing it to end users and the notification be toggled off if the user doesn't want it. It can also be kept enabled but collapsed at the bottom with no lockscreen or status bar display. Apps are required to use at least low importance themselves so the user needs to opt in to collapsing and hiding it or turning it off.

Fully open source apps can use UnifiedPush as the Molly fork of Signal does instead of their own push connection. Similarly to FCM, UnifiedPush providers can provide reliable and efficient push messaging including push notifications. Unlike FCM, users can choose the local implementation and the service providing it including the option to self-host it. There are multiple options available as an existing service. There are a growing number of apps supporting UnifiedPush.

Signal's own fallback push messaging for push notifications when FCM isn't present is very inefficient. It substantially reduces battery life even if it's the only app doing push with another mechanism. Molly's UnifiedPush support works much better.

Using a single push messaging connection or at least only a couple (FCM and UnifiedPush) is definitely far more efficient than using dozens. Using many push messaging connections will drain a lot of power due to each needing to be maintained with regular checks which will typically not align well. Having many causes a drastically higher number of wakes from sleep and non-idle time. That's especially true if the push messaging connections aren't implemented very efficiently. Even a single inefficient one can drain a lot of power.

Signal's fallback isn't as bad as it used to be but it's not efficient. They should support UnifiedPush as Molly does for a better non-FCM push experience. Signal's fallback push is a common way people ruin battery life on GrapheneOS.

UnifiedPush is an open source solution for push notifications that isn't tied to a particular service provider. A handful of apps support it.

https://unifiedpush.org/

Same for us on our Grapheneos Pixels. Notification are a bit of a lottery. But we take that as a feature. People can call if there's an emergency.

On all apps? I have never had issues with notifications...

Same, they work fine and are immediate. The only exception has been Signal. Must be that I'm using sandboxed Google Play Services?

I use sandboxed Google Play Services, Signal has been fine... I cannot say it's always immediate (I'm not always on my phone :-) ), but I have never been frustrated for "missing" a notification. Like when I check my phone, the Signal messages are there, they don't appear 3 days later.

Oh, they certainly don't appear days later. But sometimes they do between ~1-30 minutes. This is a well-known issue, you can find many topic about it. When you open the app, everything comes in all at onec.

It is sometimes annoying to me. I cycle a lot and sometimes my wife or somebody else sends a message when I'm on the go (like picking up some extra groceries) and then I miss it.

There is a longer discussion with various people here:

https://github.com/signalapp/Signal-Android/issues/14166

I see, I don't know. 1-30min could totally go under my radar :-). When it's urgent I ask people to call me.

So yeah, I can totally accept that this may be a thing.

Some don't work at all, bc they must be GSF-only I guess (installed via Aurora store). Others like Whatsapp or Signal sort of work but sometimes the app seems to not be running (even though I set up the no battery optimization). And I get multiple unread messages at once when manually starting the app.

If you aren't using sandboxed Google Play then you're not going to have push notifications in apps solely implementing those via FCM. That's your decision and not an issue with push notifications on GrapheneOS. You're using the fallback push notification systems in WhatsApp and Signal rather than FCM. Neither app cares much about those fallbacks. If you want reliable push notifications without FCM for Signal then you need the Molly fork of Signal with a UnifiedPush provider. There are hosted UnifiedPush and MollySocket services so you don't need to host it up yourself.

Thanks for the tips. To be clear I absolutely wasn't criticizing GrapheneOS in any way. I know things are this way (and my choice) and I'm perfectly fine with it.

In any case, many thanks for your work. GrapheneOS is a breath of fresh air in the consumer electronics nightmare.

That's a very important bit of news to me. As someone that's considering GrapheneOS is there guidance on these decisions either in device or a new users key concepts article I need to read?

There are a few ways to address that. I run Molly in the Owner profile without Play Services and it's been solid.

You may want to peruse the various sections of their site before switching to see if you think it'll work for you: https://grapheneos.org/features

I recommend reading https://grapheneos.org/usage and https://grapheneos.org/faq, at least in parts. You can take a look at the table of contents and see what's relevant for you.

I wonder if they installed something like "adblockers" in their devices on networks that constantly kills keep-alive connection to Google servers which actually delivers the message.

Or somehow broke the device-side wakeup for that keepalive.

Push notifications work reliably on GrapheneOS via both Google's Firebase Cloud Messaging (via sandboxed Google Play) and UnifiedPush. Your later replies indicate you aren't using either of those but rather app-specific fallbacks. WhatsApp doesn't implement a reliable fallback. Signal's fallback should work fine but is very inefficient compared to using either FCM or the Molly fork with UnifiedPush. Both FCM and UnifiedPush do work reliably.