It's a good question. I've looked at PinePhone, but last time I looked at it in detail it was light-years outside my needs for usability (very much a "we are CLI authors and are trying our hands at a mobile UI as a hobby" situation).
I think I'll look into what Android phones are out there that aren't glued to the Google Play ecosystem. Side-loading is still a feature the OS core supports even if Google switches it off (for now, and AFAIK the OS is forkable if they press the issue).
I think the only thing hat can save us is a jailbreak. Either for iOS or Android to let you sideload apps.
Alternatively, and that’s almost bullshit, the dumb phone trend continues and we might get devices like PDAs. Get a dumb phone and a small camera and then your PDA for everything that is essentially an app. Not sure what OS they’d run but I don’t see another way.
Damn the future sucks ass.