How to install games and apps on Steam Deck
Emulator playable on Steam Deck
Steam Deck runs not only Steam games, but also various emulators. Here is a list of emulators that can be played on Steam Deck.
Can I use Virtualbox with Steam Deck?
If Virtualbox, a virtual environment, can be used with Steam Deck, it is possible to easily use Windows on Steam Deck. However, whether this is practical or not is another story.