AMD stripped [Transparent Secure Memory Encryption] from its consumer CPUs

For now. There’s only a handful of manufacturers who allow you to unlock the bootloader and install another OS (and by that I mean another Android distribution, like GrapheneOS, rather than any OS such as mobile GNU/Linux distributions.) Google is locking down sideloading for “uncertified” developers, which won’t directly affect open source Android distributions, but indirectly it might because some FOSS app developers will throw the towel. More and more stuff is also moving from AOSP to Play Services and an increasing amount of apps now require strong Play Integrity (which does not pass unless you’re running the stock ROM). At the same time, more and more stuff requires a phone app (e.g. banking, digital ID, age verification, government apps, your country’s favourite messenger app) with no alternative offered if you don’t have a compatible device.

I’m personally quite pessimistic for the future regarding Android and smartphones.

If Google wanted, they could decide tomorrow to stop bootloader unlocking on their Pixels (it requires online approval after all) and also require all apps available in the Play Store to use strong Play Integrity checks. So - no more hardware (except maybe Fairphone and Sony and that upcoming Motorola flagship), and no more apps (except the open source stuff you find on F-Droid and Github). If they wanted to, they could end the viability of projects like GrapheneOS or LineageOS over night.