It's not exactly that "nobody is working on it". There was some initial work on suspend done already, you can flash a different ATF branch and get it to suspend and resume just fine - it's not used by default as currently you have to choose between suspend or DRAM frequency scaling. It's just not the top priority right now, because we're focusing on runtime power management and other promised features like DisplayPort first and there are still some things to do before it actually makes more sense to go back to suspend.
If we worked on suspend instead of runtime PM for the past half a year, we would probably now have 100h+ suspend time that would go down to 2-3h as soon as you kept ssh connection open or did anything else that would prevent it from suspending. Or even actually used the phone.
Also, just being able to suspend is one thing; but there's a ton of work still needed to properly utilize suspend from userspace, so you can still keep things like IM or e-mail notifications working transparently. The less power the phone uses when not suspended, the better - at this moment, suspend would be just a band-aid.
Have you considered how much good press the suspend time got the Pinephone? And how it is one of the key features people talk about - as in, how long the phone will last? And how in these threads people keep asking you about it? And how you could have that good press?
From your comments I worry you are only looking to release such a feature when you've fully implemented every system involving it. I realise this is very easy for me to say from a backseat position, but maybe bump it up the release schedule, and then those that do have librem 5s could at least have a 103 hour tablets that sat in their pockets, not a 5 hour paperweight that sat on their shelves until they wanted to charge it and play with it again. If nothing else, it will completely change the y scale on your bar charts.
I've been very much enjoying the updates around the librem 5 and hope everything goes well for your product.
Focusing on suspend time first may be worth it marketing-wise, but in my personal opinion that would be kinda deceptive.
Last time I worked on this kind of thing there was great kernelside suspend support that works, but in terms of userland there was no generic linux arrangements for this kind of finegrained management of it.
I also understand the point that for users, atm they just see no ability to defer when they will use the phone while it's still needed to receive calls, which is fatal. It seems properly solving this needs a new, separate userland project somewhere.
A distant future. A Purism employee (who will probably show up here since he takes part in each HN thread related to Purism) said nobody is working on it. So don't hold your breath in the near future.