Oh, Project Treble is in full swing, which is one of the main reasons you now frequently see Android phones with 3+ years of software support, often even with multiple Android OS version updates.

Project Mainline is the other thing that caused OS updates to be rather lame. Since increasingly many former Android components are now just apps updated over the Play Store, there are less features in each Android update. For example, back in the day, even the Android browser was part of the OS and would only be updated when the OS was updated.

Now Google is even throwing apps like the dialer and the messages SMS app out of AOSP.

With so little of what used to be Android remaining inside Android and these outsourced components following a different release schedule, Android OS updates are mostly limited to UI refreshes or under-the-hood improvements.

But while this makes OS updates less exciting, it also means that you get improvements faster (because components don't have to wait for the next OS update) and longer (because you get component updates when your device manufacturer dropped support for your phone).

Regarding the share menu:

There is actually only one OS share menu, but different apps sometimes implement their own share menus, which is dumb, but not really Android's fault. But yeah, the product managers at Firefox for Android are peculiar, to say the least.