Which means a bit of hacking, which means you should already be capable enough to install emudeck on your steam deck. Which is vastly superior to any single emulator on steam itself.
Yet.
>Where can I download game ISOs/ROMs ?¶
>Short answer: You don't. Buy games and dump them with a Wii.
>Long answer: Downloading commercial games is illegal and thus strongly frowned upon by the Dolphin developers.
[1] https://dolphin-emu.org/docs/faq/#couldnt-dolphin-use-more-m...
Ps this is not a moral judgement, I would use it myself except I don't like Nintendo's style of games. I owned a Wii and bought some games but I was really bored. I modded it and downloaded everything I could get and not a single game could capture my attention. I missed good fpses, it was all party games and kiddyish/cartoonish stuff like Zelda and Mario. So I've never looked at Nintendo since. Perhaps these days their offers would be more interesting to me but I haven't checked.
This was in the early days of the Wii though, when it was still a big hype. So all the games I tried were launch titles or very soon after. I thought the motion controller thing was not very well worked out and more of a gimmick. I was expecting it to be more exact like with VR controllers these days.