The Steam Deck is the best device for old games and old game emulation. If you want to play newer games it’s woefully underpowered. Something like RDR2 or like The Witcher 3 are vastly superior on a Lenovo Legion Go. More powerful and with a much bigger display. I’ve had both devices and they both do different things well.

Detachable controllers and two USB-C ports are really nice on the Legion as well.