

you should aim at $100ish (used obv) and make it as fungible as possible. a lost or stolen or exploded phone is then a no biggie. it’s encrypted by default so nobody can get at your shit, it’s easily replaced with another one, restore data, roll on. so it doesn’t matter which one you get, as long it has official lineageOS support. go to https://wiki.lineageos.org/devices click on “filter” and choose the latest LOS version (22.2 as of now) and then pick and choose whatever’s in that budget.
edit: replacing the battery on the 6a is also possible, youtube for details; not the easiest thing out there but not that hard either, especially when it’s doomed anyhow.
I have no alternative but used phone + lineageOS; the stuff you’re mentioning (new phone with whatever crap they installed on there) isn’t even on my radar as an option.
as to longevity, it’s a stop-gap to hold us over until postmarketOS or any of its brethren are ready. banking on the benevolence of evilcorp to give us this thing for free for ever isn’t a viable strategy.