Yes, you can enable it in your the LibreWolf specific UI or in your overrides. There aren’t significant downsides as Firefox Sync encrypts your data locally before transmitting it to the server. Additionally, you can self-host the old version of the server if you really don’t want to use Mozilla’s, and there’s work being done to have the new version equally easy to self-host. Find out more about the technical details of Sync’s implementation here and here.
When using Sync across multiple installations you might want to disable settings synchronization to avoid unintentional changes.
Are you trying to install an update from GitHub to F-Droid app? This will not work because F-Droid apps built with different signature. You should uninstall F-Droid app in order to install updates from GitHub or Play Store. Or you can add source from F-Droid to keep updating app from there.
We’ve already tried to build a join-lemmy.org banner and almost done. We made allies with some communities, but the bigger ones are too hard to reach out.
There is a Matrix coordination chat, join here to help us: matrix.to/#/