This idea is about as realistic as breaking up Germany into its constituent Länder so they'd get more EU commissioners.

Illegal without 100% consent which renders the idea moot - except just maybe in the case of Texas, which had a special clause during accession to allow division into up to 5 states. It's not entirely clear though whether the clause still allows that (or did it apply only for that particular congress).

Well states don’t have the power to do that. So not a very “easy hack”.