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.
Island is great. My wife runs ecommerce and social media accounts for her job (and has her own side business at home) and used to use 2 phones, with Island she can run parallel sandboxed copies of certain apps at the same time (ebay etc). It’s the first thing she installs on a new phone and at this point she’d refuse a new phone if she couldn’t use Island on it. With the normal work profile, she’d have to constantly switch between profiles and miss out on real time notifications.