Seconding this. I use Obsidian and Obsidian Sync for personal stuff, but my employer doesn't allow Sync, so I use Obsidian very happily as a standalone on my work computer. The work vault simply never gets exposed to the outside world (we don't allow USB memory devices either).
For those that want to sync without paying, many use syncthing, though I don't think this is a feasible workaround for iOS users.
There are some other syncing methods that I haven't really looked into.