I like the idea. Subaddressing with a + on my gmail addresses has been very useful, but I like the idea of it being a first class citizen.
Is there any chance that a hyphen will be rejected by some online forms? Even if it is is valid, there are some bad validators out there. I'm just thinking it might not be possible to use this for some of those services if all emails to your base address get bounced.
And bringing my own domain sounds interesting too.
This is pretty similar to Beanie Babies, but not Pokemon or Pog because you could play with those. Beanie Babies were popular for some reason (right place right time? Brilliant viral marketing?) and then became an investment opportunity. Same with Labubu. I've always seen talk about how much they're worth, and the blind box adds a bit of gambling to it, which I guess is similar to opening a pack if cards.