I just got a smartphone, after putting it off for decades. I've pared it down so that it only does 2 things in the background... take phone calls, and SMS. I've turned off all other notifications.
I bought it in the first place to do 2fa, which works.
I don't use it any more than I do my old dumb phone.
Why would you do anything other than take calls or texts on a phone?
As for desktops/laptops, there are no safe operating systems suitable for use on the internet. Contrary to your opinion, Linux isn't safe, neither is Windows, MacOS, iOS or Android. Nothing supports capability based security. Nothing will be safe until it's in widespread use. The fact it was invented in the 1970s and remains largely unknown is proof we're on the worst timeline.