I did a similar thing. I replaced my iPhone (after I dropped and smashed it) with a Nokia 105 "dumbphone". It can only do calls and SMS messaging. It's the best thing I've ever done. I knew I'd get by without most things but I wondered how I'd get by without google maps in my pocket. I bought a road atlas for the car and quickly re-learned how to read a map and plan a route the old fashioned way. If I'm going somewhere the seems remotely complicated to find I'll just print off a google map before I leave. Looking back now, it's scary how reliant I'd become on dumbly following google maps turn by turn directions.
Emails, again I simply deal with the way we used to before smartphones. As and when.
Most 2FA systems also still support SMS as an option so even that's not a limiting factor of using a dumbphone.
My new phone cost me £10 and costs only £5/month to run because I literally cannot use any data.
The only downside I've encountered is the feeling that others are being ignorant/rude whilst blankly staring into their phone. You don't notice this when you're doing it too, but it's really very noticeable once you stop.