I mentioned this in another thread about the same thing. The Samsung Galaxy S3 was great for that. It was a 10 second job to pop off the back cover and swap out the battery. No risk of breaking the screen, no glue, no miniature cables to unplug and replug. That really should be the norm. It would be even better if we also didn't have to buy expensive branded batteries to replace them.
It also had an official extended battery, which came along with a special backplate. It made the phone a bit bulkier, but I didn't care. Battery went from 2100mah to 3000mah and it was great. I miss these types of accessories. I don't care about glass back or waterproof phones.
Waterproofing _is_an important factor for sustainability for phones though. Water damage was THE cause of death of smartphones for a very long time until waterproofing became the standard for phones.
My first iPhone was in my coat pocket at work. I picked up a bottle of beer that was juuuuust cracked enough that it would split around the middle from the slightest bump but not enough that the liquid would leak.
I stuck it under my arm to carry it and it split and spilled into my pocket. Not a lot made it in there but the phone never powered on again.
My Nextel back in the 90s had the same type of extended battery. Thick as hell by today's standards but it didn't actually fit better or worse in my pocket or my hand. Also didn't feel like I needed an external case just because it might slip out of my hand at any second.
I’ll 100% prefer a thin but still repairable device that requires disassembly and common tools to replace the battery. Its not something that needs frequent changes any more, most devices can go 2 years plus and before the battery really needs changing, more if you take care of them.
For the Steamdeck it makes sense to have “old school” battery packs so people can choose. But for that same reason, it would be stupid to require by law for all devices to support hot swapping batteries.