I use the Librem5 as my smartphone. SMS and phone calls work good. I'm using Nheko as a matrix client - works great. Geary as an email client is kind of a pain, but can definitely be relied on. Tootle is a great software for mastodon.
I wouldn't say the phone is ready for people without any knowledge in linux, but they are getting there.
More on that here: https://source.puri.sm/-/snippets/1188
BTW: the last phone I saw overheating has been the sony of my wife.
