I have gone through three systems for contact syncing since transitioning to an open source tech lifestyle with my switch to Linux in August 2020. I tried EteSync, Radicale-DecSync, and most recently, using Posteo for server-side address syncing. Today I changed approach, borrowing from the Radicale-DecSync idea, which involved Radicale running locally on my computers, the DecSync app, and Syncthing. I first removed Posteo Sync on my GrapheneOS-powered Google Pixel 6a and then exported the .vcf file to a folder in my “Sync” directory that I Sync to my devices with Syncthing. I deleted my contacts from Thunderbird and imported the .vcf. After some testing, I opted to use Fossify Contacts instead of GrapheneOS’s default AOSP-derived contacts manager because the import and export was more to my liking. I then made some changes on Thunderbird, exported the .vcf, and imported them into Fossify Contacts. It worked as expected. I will keep playing with this system and see how sustainable it is.