I used Mint for a long time, I like it and Cinnamon. My laptop at home is running LMDE (Linux Mint Debian Edition), which is not based directly on Ubuntu like “normal” Linux Mint, and it works great.

I recently set up my desktop with Debian and KDE Plasma and think that will be my standard build moving forward. I have some home servers that are running Ubuntu and I was planning to rebuild with Debian anyways, so a Debian baseline across all my machines makes sense and should be easy to maintain.

I prefer not to sync my information with Google or other entities either, but do not think that using Linux precludes using whatever tools they like. I don’t think this is a question about ideals, but about tools and compatibility.

I personally also doubt that Google Tasks supports that capability, unfortunately. I personally use Thuderbird for email on Linux, and it supports tasks too (I use Nextcloud for my tasks but I bet it supports Google as well). Not the same as your gnome extension, but an option.

Good luck!