Is this still in development?
It has been three years since the latest version was compiled, and there have been very few updates in the GitHub repository.
Nextcloud app Global site selector is for version 19 of Nextcloud.
When looking at Nextcloud’s website, they mention this project extensively, but there is no information available unless you are an enterprise customer.
So, is the actual project behind a paywall?
That’s a good question.
There has been activity:
https://github.com/nextcloud/globalsiteselector/pulls?q=is%3Apr+is%3Aclosed
And there is a maintained CHANGELOG there.
Many Nextcloud hosted apps don’t get released via the normal Releases spot in GitHub. The specifics vary depending on the type of app (shipped and default apps for example).
That said, I’m not sure where the release artifact is for GSS or why the appstore entry for it has gone dormant. Typically that only happens when an app transitions to being shipped[1][2]. But that isn’t the case here.
The code is all there in the repo though (you may have to look at the stableXX for your target Server version). And a maintained Makefile (which looks sane to me from a quick look).
Perhaps open an issue in that repo if you feel so inclined and see if someone involved with GSS responds? I think someone else asked here not too long ago as well and I never got around to following up on it.
[1] https://apps.nextcloud.com/apps/suspicious_login
[2] GitHub - nextcloud/suspicious_login: Detect and warn about suspicious IPs logging into Nextcloud