A local volunteer group has a few people maintaining a single site. They don’t update frequently and the chance for concurrent actions is low.
Right now I sync using a 3rd party tool (syncthing, it’s truly awesome free libre open software) to keep the whole Publii/sites folder synced between all of them. This works to a large degree (already had issues with plugins and themes).
Maybe it could be considered to foresee a different system, where Publii, upon publishing, automatically makes a “backup” of the site-source and uploads it to the webserver (to a safe spot like outside the webroot). Then it could be a setting that, upon opening the site in Publii, it would automatically download said backup, uncompress it and seamlessly present that to the user for work.
It is a large extra responsibility, could potentially cause conflicts and maybe better served in another manner, but it sure would fill a void.