We've been trying out "Dropbox" (-i.e. not necessarily specifically "Dropbox" but any old cloud will do; "sharefile", "dropbox", "nextcloud", "onedrive" etc.) for a while now and it's working out fairly well. A few issues but typically we have only one person working on a task at a time (everyone is just too busy to be mulling around). When we do share a model among several people we have to coordinate sync times but overall it (the duct tape solution) is working really well. In the decentralized spirit of methods I really liked the "Syncthing" method we tried out a while back. Syncthing isn't a cloud, its a Peer-2-Peer thing, that gave us more security (and I could manually control what was and what wasn't sync'd). We do this because VPN is so slow and with the cloud setup we sync files amongst ourselves almost as fast as if we were on the same network. At worst there is a few seconds lag between me and someone across the country.
The problem with Revit and a cloud or P2P solution (and your problem too) is the *.dat files revit needs to sync ("wperms", "eperms", etc). The wperms and eperms.dat files are the workset and element files which tells your revit what is and what isn't locked (revit pings and saves these files every second or so).
You shouldn't necessarily have a problem with worksets and VPN but honestly you need to kill the use of worksets in your projects and rely on filters and visibility graphics (view templates). Worksets really are not needed in your models (unless you're dumb enough to have every discipline--a,s,m,p,e,c...--in one model) and are a really misunderstood aspect of Revit. Worksets are not a "AutoCAD Layer thing" -e.g. they are a method to turn off an entire discipline in a multi discipline shared model (just a vague example). ...If you're a boss (decision maker) I can give you the direction you want to tell your people to go down otherwise we can talk specifics if your up for it.
AutoCAD is a different beast; sheetsets are a royal pain the ass with any solution (other then VPN)!