I've had my Steam Deck a few months so I'm comfortable getting around. That said, it could do a lot that it isn't. Partly because the default desktop experience is so barebones and has kinda bad ergonomics.

I know there's emulation and such that I'd be interested in. I'm a linux nerd so don't be shy. I'd say the main thing I'm looking for is for the Desktop mode to be more of like a "default to Couch Mode: unlocked, but can go to a (nice) desktop if need be". I really like the idea of playing my GOG games, emulators, etc all in one menu that's ergonomic to controller. I have a file server handy as well, anything good to do with that in conjunction?

Besides that, what good/cool uses have you found?

I dream with a new mainstream handheld console that is neither an extension of a regular console experience, a smartphone, or a wine-powered Linux machine

When I was a kid in Brazil, we had a manga and anime club in my town. It was somewhat official. At our gatherings, there were lots of manga and VHS tapes that we exchanged and duplicated when possible. There were always two or three kids, each with a Nintendo DS. Sometimes more. For us, they were the rich kids. Back in 2005, it was unimaginable for most kids to own a DS, or even a Game Boy for that matter. They connected their devices and played some kind of Pokémon. I pretended I did not care and did not pay them overt attention. My envy knew no bounds.

At least a decate later, when the PSP was already going out of fashion (and was therefore much cheaper), I managed to get a PSP Go. It came fullly cracked with hundreds of games. I loved that cheap little thing. I eventually graduated to a PS Vita, which I believe was the finest piece of hardware I ever had in my hands. But the proprietary memory card was pricey, and so were the games. I didn't have lots to play. It's a bittersweet memory.

Seeing how the Vita became an emulation powerhouse makes me regret selling it.

I never owned a Nintendo DS, but a friend of mine lent me his for several years. I loved that too, but the stylus felt like a gimmick, and I would have gladly swapped it for regular controls. I was not a fan of the dual screens either. But at least it was interesting, you know? They were trying to do something different, and I respected them for that.

Now I have two retro handhelds, the Miyoo Mini Plus and the RG35XX H (Anbernic). Cheap Chinese products, but decent enough. Setting them up correctly was not hard, but it was laborious.

Maybe I am crazy, but I still think handheld consoles could work in the mainstream. It won't happen, of course. But it would be awesome to be excited by hardware once again. Something unique that is not a phone or a way to play Windows games on the go. With games that are developed explicitly for handhelds, with UIs that are adequate for small screens and crazy features that wouldn't make sense in the living room. A sturdy piece of tech that is always there for you, suggesting nothing but escapism.

One can only dream.