If you don't need anything more powerful than PS3/X360, then a steam deck is overpowered. A second hand laptop with a dedicated GPU will be enough for everything up to GC & PS2.
There are other retro handhelds in more varied form factors for much less if that's more your cup of tea
There are other retro handhelds in more varied form factors for much less if that's more your cup of tea
alternatively if you feel like drop 800 euros (or possibly 900) the "Xbox" Ally X from ASUS ROG is going to be a decent contender for "gaming on the go"
i frankly thought of it and then i remembered i can just emulate PS2 games on my ROG phone so buying a steamdeck is kinda redundent for me