I use Syncthing-Fork, by the way, just a note I forgot to add. More features.
I let it run 24/7. It’s been running constantly for months. It uses less than 1% in a day so it’s reasonable to not have to turn it on when I want to sync.
I have no idea if collaboration is a functionality of the paid obsidian features, it could be, but I don’t even have an account with them. Syncthing doesn’t support this (its just used for syncthing files to multiple devices), however you can share a note and edit it as long as you are not editing it simultaneously. Like, a back and forth kind of deal.