On the same topic, and because I believe too that WebDAV is not dead, far from it, I published a WIP lastly, part of a broader project, that is an nginx module that does WebDAV file server and is compatible with NextCloud sync clients, desktop & Android. It can be used with Gnome Online Accounts too, as well as with Nautilus (and probably others), as a WebDAV server.
Have a look there: https://codeberg.org/lunae/dav-next
/!\ it's a WIP, thus not packaged anywhere yet, no binary release, etc… but all feedback welcome