Google has it, though I think you need the paid Workspace version? I’m paying around $15/month now ever since google killed the free tier for custom domains.
Not sure about Apple, but Google calls has that and calls it catch-all-routing.
I don’t know about Google, but I know iCloud supports domain wildcarding
Proxy address ie user@gmail.com you would use ia+user@gmail.com and have rules to match that
It’s user+ia@gmail.com, and it’s a poor substitute for a dedicated domain. For one, every attacker knows about plus addressing and that those addresses are really all the same email account.
They still don't know what you put after the "+" to log into another service.