Sounds like you already know what you have to do, you just have to do it.
In my own de-googling I’ve learned the more you de-google, the more perceived “conveniences” you have to give up. Unfortunately, there really aren’t a lot of all in one NFC payment solutions on F-Droid/Foss.
LineageOS is good enough for privacy/security assuming you practice good digital hygiene. Its kind of a double edged sword there.
A cool bonus with foss apps and OSes, is generally, their software are more optimized and not resource hungry. Meaning, you can run older devices without any issue. You could probably find an older pixel and run Graphene on it no problem.
If you want to completely de-google, you have to leave their walled garden behind. There isn’t really a one leg in, one leg out solution.
It’ll be awkward and frustrating for a couple of months but then you’ll never go back.