My mom, who used dialup as recently as 2019 (not AOL) used it almost exclusively for email...Gmail's simple interface. She had a very active group of email correspondents, but Gmail on Chrome was her only need.

I've got in-laws that use 12yo Macs; would not surprise me in the least if a lot of older folks were still using whatever box from Best Buy or a relative they got in the late 00s.

Judging from how Amazon loads now on modern speeds, I'm guessing Amazon is out of the question.

Email should be fine... as long as you don't use a web client.