Batteries will be in bad shape.

Can we do 2010s phones with 2020s battery tech and modems please?

'replaceable battery'

"chart of phones with replaceable batteries": https://news.ycombinator.com/item?id=47099020

it is very difficult to find good (as in "good condition") battery for a 5+ old gadget. even if you find original one - it could be expired and DoA. but more often you get "compatibles" which die in 3-6 months.