Syncthing is definitely nice if you just need p2p sync between devices though.
If you need more than that, like a web portal full of your files, sharing via web links, etc.... Try nextcloud.
I might, but I'd want to hear a lot of reassuring words about security.
To a sibling comment's point: yes, syncthing is p2p, but I'd like to have one of my instances be somewhere off-premises and running all the time so I can synchronize between my office computer and a home computer without needing both of them running at the same time.
I guess someone could offer a service based on it with theirs being the hosted/cloud node, perhaps like a “master” node I guess? I’d imagine they’d have to hack on the syncthing code to achieve this? Not sure...