For me it’s Whatsapp. Like 99% of people i know use it so yeh… i still need it. I am considering moving the Whatsapp Gdrive backup to a local backup btw.
Google photos is also a major problem for us. We have a lot of stuff that want to migrate to different service (or store locally).
I couldn’t talk anyone into Matrix (Or Stoat or any of the others) but I somehow managed to get a Steam group chat sort of rolling instead of Discord, as most of the groups I played with had Steam accounts anyways so it was easy to jump on.
Not ideal, but its some progress?