If you’re looking at getting a new (used) phone, I would suggest GrapheneOS (the most secure/private de-googled rom afaik).

You need a Pixel phone, the newer you get the longer you will keep getting software updates for the future (if you keep the phone past these many years of support, then I believe switching to a other rom will be required for security patches etc. Each phone is supported until Google stops supporting them I believe).

If you plan on never touching a google service, GrapheneOS allows for that (nothing google by default), but on the other hand, if you need google play, etc for banking apps or whatnot, they have that covered with Sandboxed Google Services (which you can run solely in another user profile on your phone for added privacy).

Anyways, I think GrapheneOS in a great option & their website has much more info if you’d like to continue hearing about it:

grapheneos.org