ga2mer

Some powerful retro handhelds support Linux loading, such as: Retroid Pocket 5, Mini, and Flip 2 on the five-year-old SD865, and more recently, Ayn Odin 2 (original, Mini, and Portal) on the three-year-old SD8 Gen 2 (which is one version lower than the SoC in Steam Frame (SD8 Gen 3)).

So if we get a native arm version of Steam and Proton ARM64EC, we will essentially already have mini Steam Deck(s), and since you want something similar to a PSP, you can check out the Ayn Odin 2 Mini, it's similar to the PS Vita, but I'm not sure if it's still available for sale, or you can order the Retroid Pocket 6 (available in a few months), which has the same chip, but a better screen and is also small in size.

Amazfit's Zepp OS uses quickjs to run 3rd party watchfaces and apps in their smartwatch

I was surprised to find out I'd been wearing javascript on my arm all this time

>you can just use postmarketOS

Only if your device is fully supported

I have about 5 "post market" devices and only two of them have any support in postmarketOS: Redmi 4x, in which hardware acceleration does not work and I have not been able to run any DE on it and Pixel 4a, in which judging by the pmOS wiki page works just about everything except the most important part of a modern phone - touchscreen

Google is quite sneaky with updates: I own a Pixel 4a, which has guaranteed major updates ending in August (in a few days), but it's like Android 14 is purposely delayed and will come out most likely in September and thus skipping the 4a