There is an element of tragic comedy to those announcement. While remarkable on their own, everybody knows that one cannot use any new browser feature reliably any time soon due to Apple not shipping continuous updates to the browsers they force upon their users.
Safari got a big update last week.
iOS from 2 versions prior don't get latest Safari?
I can't check because my wife's iPhone is, regrettably according to her, "updated to the latest glAss version".