datalad-annex supports cloning from the web special remote, using an url that contains the result of pushing to eg, a directory special remote.
datalad-annex::https://example.com?type=web&url={noquery}
Supporting something like this in git-remote-annex would be good.
The httpalso special remote already exists to handle this kind of thing.
In fact, it just works with git-remote-annex!
Eg, this url on my laptop is a directory special remote accessed via the web server:
annex::13c2500f-a302-4331-9720-6ec43cb8da2b?encryption=none&exporttree=yes&type=httpalso&url=http%3A%2F%2Flocalhost%2F~joey%2Ftmp%2Fd
But, while fetching from a httpalso special remote works, and cloning works, after cloning, fetching again fails:
joey@darkstar:~/tmp/newp2>git fetch origin
git-annex: no url configured for httpalso special remote