I'm running a Steam OS like experience on my Lenovo Legion Go. Not quite a steam deck, but very similar.
You should be able to use the heroic launcher. And you should be able to install it as a flat pack or a snap. That will make your GOG games as easy to download and install as a steam game. If I recall correctly, it even automatically adds entries for steam.
I regularly play Bomb Rush Cyberfunk on this device using the GOG edition.
I had a unique upbringing. My father was an illiterate dyslexic (and maybe autistic himself) and he is fuckin weird - to put bluntly. That side of my family never really understood neurodivergence per-se, but they understood that everyone's a little weird - but we embraced that we're VERY weird. Hanging out with my dad's extended family is a lot of flailing, weird humor, and zany shenanigans and they embraced every moment.
My mother by contrast was more "abled" but she relished the "weirdness" that my father had in spades. Her own family had a bit of a zany streak as well - with my maternal Grandfather very obviously being undiagnosed autistic and having his own brand of severely understated and jump-scare humor.
Masking was entirely unnecessary in my family - and I can recognize the state pretty easily. It's more mentally relaxed, less hypervigilant, and generally more comfortable.
It was great not having to mask in my childhood - until I went to school and it suddenly wasn't a good thing.
Learning my masks was an absolutely agonizing process because "being myself" wasn't acceptable "out there". I felt so out of place compared to my peers. I was also bullied relentlessly to the point of PTSD. My masks eventually became automatic through the tumultuous times. It wasn't until my diagnosis in my early 30's that I even began to understand what it all was, and start deconstructing the masks.
Unmasking was as easy as accessing a "younger" me and simply not caring about the social results. (to a point)
For my echolalia, I don't hold back my vocal stimming anymore. I used to feel embarrassed and self conscious around it. Now I embrace it and have fun with it. Will you get movie trailer voice me or death metal voice me? Who knows!? Will I throw a random phrase using an English accent into an otherwise monotone statement, yoooouuu bet!
For my special interests, I LET my excitement bubble over. Sure, I might need to regain my composure from time to time, but hiding my excitement about these things nearly destroyed me. I try not to be hyper-focused though so as to allow natural conversational flow, but I also don't overly police myself anymore.
There's a few other things, but it's hard to reflect on them all.
Ultimately I'm unsure how helpful my experience is to others - it's a bit unique having a deep family culture of being really weird. I think that really helps me put my guard down and unmask. If I didn't have these memories, finding my unmasked state would be a LOT harder.