Now that importtree=yes is supported for special remotes without also needing to implement exporttree=yes, it should be possible to make a lot more special remotes support tree importing.

These built-in ones could support it:

• webdav

• S3

  importtree=yes is only supported when versioning is enabled (or when forced when version is not enabled).

  It would be possible to support importtree=yes without exporttree=yes for any S3 bucket with no need of forcing.

Lots of external special remotes could also probably support it. That will be left up to their maintainers, but it would make sense to ping the maintainers.