Shelter may have been taken down a while ago, not sure if by Google or the developer.
According to the Island developer Island was removed because it’s not supposed to use
REQUEST_INSTALL_PACKAGES, so it’s probably the same for Shelter. They’re appealing but if/when it returns it might be “with limited functionality” which one would be able to restore with an “extension” downloaded on github but at that point why not just install the apk from github in the first place.
As for Shelter and Insular (fork of Island), they’re also available on F-Droid.
Wonder if they’re cracking down on these “hacks” to leverage the work profile on purpose, like they do local VPNs that block ads.
Glad its still working. I’ve been using Island for a while now. Maybe it is because I used Shelter for a long time but I like it better. I’m going to switch back if its still working :–)