I returned my Steam Deck because it's so anti-consumer.
1) Steam Deck repairability is garbage
2) Steam Deck tries to lock you behind Steam OS that only supports Steam. If you want to use GoG, Epic Game Store, or anything else, there is no support for that.
(You can try to install Windows on Steam Deck, but as LTT pointed out, and I experienced myself, this is pretty much a disaster because Valve doesn't seem bothered by all the Steam Deck issues when running Windows. The goal of Steam Deck and Steam OS is for you to buy Steam games, they don't really want you to run another OS. This is against the spirit of PC gaming imo. Asus doesn't sell games, and therefore they support anything you install.)
3) Lots of games simply don't work or work poorly on Steam Deck due to all the DRM on Steam. Steam is the major distributor of DRM themselves. Steam's DRM wrapper is used on many games on Steam, and Steam supports Denuvo on their platform.
Supporting heavy-handed DRM is a choice Valve made. People love to blame the developers for DRM, but refuse to condemn the Steam platform that willingly distributes and even develops DRM software. Stores like GoG refuse to allow Denuvo on their store.