It seems as if you add with SSH URLs, this makes the repository hard to impossible to use for those that do not have a GitHub account. You shouldn’t use SSH URLs for submodules that you do not want to write back to.
Also it seems as if those submodules are linked to a certain commit. Perhaps you should instead link them to a branch instead? This is only possible for newer Git versions though. Not sure when exactly that feature has been introduced.
It seems not pinning to a revision is not available with https protocol. I have switched to https and have a little update script in there that I think checks out the submodules to the latest version.
I’ve extended it to include @NobbZ, @davidtwco and the list that you’ve suggests and also the nix users on gitlab I could find.
That makes 74 users to grep through for examples. I’m happy with that - I should find plenty of examples of what to do.
Ah yes of course - I will have to add my own in and that will round up to 75.