Yeah, they're not gonna do that. The GrapheneOS team thinks Google will give the 6 and 7 series 5 full years of OS upgrades instead of 3 OS + 2 security tho so fingers crossed.
I'd love it too with my 7a, but there's no way Google does something nice just 'cause. They've already sold the phones with a shorter support window and they gain nothing by releasing more updates for those devices.
Definitely great to hear. It's too bad they're not bringing new pixel software features to older devices though. It'd be a great way to differentiate their lineup from the iPhone.