I bought a Deck for the SOLE purpose of being a continuation of the PSP line for me, which I CFW'd so I could play a massive PS1, GBA, NES, and SNES library on it.
It did exactly that, except then it blew me out of the water by also being able to emulate
>PSP>N64>PS2>Xbox>DS>3DS>Wii>WiiU>SwitchAll perfectly. Switch stuff in most cases even better than the native Switch.
Then for cherry on top, I knew I was going to be able to play some cool older PC games as well like Age of Empires 2, but it turns out the Deck is so strong it can play fairly modern games such as MHWorld or Fallout 4 at unexpectedly high framerates as well.
Like this dude
>>715347828 says, EmuDeck makes it all super accessible and braindead too. No need for any tinkertrannying at all. Just install, plug and play. I prefer doing it all manually so I can have it as debloated as possible though. RetroArch is very helpful for this.
As for MUH LINUX, the Deck singlehandedly made me switch from Windows to Linux on desktop because of how much better it is.
Finally, Valve keeps making updates to SteamOS and the Deck. They still somehow manage to keep optimizing it further and give you more FREE frames. Opening your Deck and doing hardware operations isn't just supported, but encouraged and comes with guides. Same with repairs. Valve is so pro consumer it will make your fucking head spin. Nintendo just wants to rape your asshole and your wallet.