Shameless plug: A while ago I wrote a cli for firefox sync [1] (in my case mostly to automate some stuff when I create bookmarks). It does not really solve you

Shameless plug: A while ago I wrote a cli for firefox sync [1] (in my case mostly to automate some stuff when I create bookmarks). It does not really solve your problem for browser-history/credentials etc. But as long as you use a client that you verified you can be kinda sure the data is E2E encrypted and can't be read by Mozilla. Also on a side note: To this day the weave protocol is one of the more (needlessly) complex protocols I ever implemented and I'm still not sure what problems some of the design decisions solve... [1] github.com/mikescher/firefox-sync-client