I wonder how much of an overlap there is between those still using classic GSM phones, and those who listen to vinyl records.

I know plenty of folks using those. Most people do it by choice because the hardware is more reliable and the battery more durable, but some also do it because their planned-obsolete smartphone broke down.

I have a smartphone, but i usually dont have a sim card. One is not exclusive to the other. I use and need google auth and some other apps, i also like to surf on my couch.

What i definitly dont need is being reachable and available 24/7 wherever i am

I've seen that many elderly folk prefer phones with tactile buttons to touchscreens, so they keep using non-smartphones.