Again, based on @FixedFun 's original designs so creds to them for the idea.
Thoughts about these ones? For the one on the right, I tried a different angle to hopefully give more bird and less bald man.
I don’t know anything about iOS development. I know it’s possible to add pills to an icon if you have notifications, but I have no idea if iOS gives you the ability to change what the icon looks like. Because we’d be talking about a PWA, the tools may also be a little different.
As for browsers, I actually misremembered how favicons worked. After refreshing my memory, This is actually much less effort than I originally expected. Assuming an instance wanted to implement this, they could just change the link that defines the icon based on the currently logged in user’s number of notifications.