My (no-carrier) WiFi-only Android tablet ... is also wholly dependent on the hardware vendor for updates, of which to the best of my knowledge has never seen an OS update since date of purchase (though vendor apps, which I've never used and cannot uninstall, have updates pushed, routinely demanding greater permissions).

Of all the monopoly-leverage-based requirements Google could make of Android vendors, demanding update SLA and EOL minima are apparently ones they've never contemplated.

0/10, would not recommend, ever.