This seems more applicable to consumer products, not business / cloud services, though I imagine I might be overlooking something.

That's a fair observation. I do go back and forth but in the end it's enough to swing me, in the principle-of-least-regret way.

It seems like a pretty reasonable concern to me. We can presume the odds are pretty low, yeah. But the consequences are very high - you would need to redesign and possibly rewrite in another language your entire application. People complained up a storm about Reader dying, but it was a 5min process to export your subscriptions and import into another web reader that had basically the same feature set. Conventional Linux hosting, or even Docker, could be pretty easily re-hosted as-is on any of hundreds of other places.

So what do you use as the backend for now?

I usually go with a Django or RoR monolith, something that I know I can run on a cheap DO droplet or similar, and while there's a fixed monthly cost it's reasonable and I can scale up with ease (albeit manually). If I were explicitly needing the realtime DB aspect I'd probably look to Phoenix with the same hardware approach.

It would be nice if there was a dead-simple Firebase-like tool you could self-host. ie just a single instance that you could point all your toy apps at to give them a little real-time persistence.

Around the time that Parse (mentioned by sibling) was killed and open sourced, a lot of open source Firebase-like solutions had sprung up, some of which are listed here: https://github.com/relatedcode/ParseAlternatives#open-source...

Parse was a Firebase competitor that got bought by Facebook and later open sourced, I don’t know if it’s dead simple though.

https://parseplatform.org/