Just send them the app url and let them know you do private chats on a private messenger. Show them all the fun stuff like stickers, GIFS, groups, stories, etc. Save the delete messages stuff for later.

Pretty sure they log your IP

I think Posteo works for this as well. Could be wrong

Just let them know you don’t want Facebook having anything more on you than they already do. Let them know it has everything people want in messaging apps like stickers (whatever the heck those are?!), GIFS, video and phone calls, groups, etc.

Yep, should serve as a corollary to the “cloud is just someone else’s computer” meme.