> It's a redundant renewal of the existing Pfizer under the exact same EUA
No, its a full approval of the existing Pfizer vaccine for those 16+. The EUA remains in place for younger people 12+.
> It "pre-approves" a new future Pfizer vaccine
It doesn't, I guess this is a misreading of the fact that the approval of the existing Pfizer vaccine includes, as such approvals do, the marketing name of the vaccine (“Comirnaty”), but this isn't a new vaccine, just the brand name for marketing the existing one.