Criteria and absurd wishlist
Affordable, might find it used in a shop in the u.s. or from a reputable source online
Full Root
“Secure”
Quality build
Removable battery/sim/storage
Headphone jack
Tablet or phone
Runs something better than Android 7
Samsung Galaxy S5 checks all of these. I prefer it with Lineage 14 (Android 7), but ran it with Android 8, and it can support up to Android 10 or 11 IIRC, although later versions are somewhat slow.
Samsung Galaxy J7 (2015) might also fit the criteria, even though it’s not a “flagship”.
If you’re looking for alternate OS list for smartphones and tablets, I compiled a list.