Contacts backup?

Hi I have been running graphenOS on a pixel but have not fully committed - still running it SIM-less on wifi while on the habit of getting used to it and seeing if I can fully commit. I'd like to de-google as much as I can but not sure what to do about contacts - which has been using my google account for years.

I am a home-labber and like the idea of running a calDAV server to manage and back-up to NAS and proton drive but that's a lot of set-up up front. Wondering what the community currently does. Can you share what you use for managing and backing up contacts?