I have similar function requirement. Based on your TRAMP method, I think remote file are just can be transported through any protocols like HTTP, for example remote file like http://example.org/test.org can be downloaded, then append to org-agenda files list. This is just an rough idea.

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On Mon, Nov 20, 2017 at 3:54 AM, Eric S Fraga <esflists@gmail.com> wrote:
On Sunday, 19 Nov 2017 at 11:10, David Arroyo Menendez wrote:
> Hello Colin,
>
> org-secretary seems designed to manage teams. I want read agendas of
> org-mode users, friends ... In Barcelona Supercomputing Center all
> people is sharing the agendas to stimulate to the people to collaborate
> in good ideas, I like this methodology, but I prefer use org-mode. Many
> people in org-mode is connected with the science or creative
> programming, perhaps is a good idea share the agenda between us.

I guess one approach could be to make specific agenda files available on
a remote server and use tramp syntax to add these files to the
org-agenda-files variable?  (untested)  Of course, this would be limited
to those access methods defined for tramp, i.e. ssh in practice, which
might be quite limiting.

A more general approach would be to export your agenda to Google's
calendar or equivalent and share that and import any shared calendar
using an ical access to these.  This is possible (my wife and I share our
calendars that way) but not purely org.


--
: Eric S Fraga via Emacs 27.0.50, Org release_9.1.3-162-gde289d