I once again dream of

* An AMD Ryzen/Atom without 32bit
* With E cores only
* With a Radeon iGPU that's slimmed down
* In a smartphone-sized enclosure
* With a Quectel model
* With a battery
* And running SteamOS or postmarketOS
* That I could use as a phone

Pure Linux without Google?

GIB.

I'd like a passively cooled clam shell handheld the size of a New 3DS (not the large one) with amd64 SteamOS

There are so many indie games out there that would run no problem on something like that and it would be a true pocketable handheld.
My Steam Deck has been gathering dust because it's just too big to feel like much of a proper handheld. But the second someone gets SteamOS running on something that actually fits in my pocket? They get the entire contents of my bank account.