Is the Nintendo/Playstation version of the game allowed for submission? Or will there be a separate category for those platforms?

It is surely allowed, despite not having a leaderboard yet. It would be in a different category since I guess there's no QS/QL on console. What is you run ?

I didn't do a run yet but I want to do one soon. I wasn't sure if I could submit a Switch run of the game here or if it would be a different place.

This game has always has a console version on original Xbox, yet no one has submitted an Xbox run in all these years. Perhaps a separate leaderboard for console would promote more diverse platform choice, especially with the newer releases of the game being out there.

For now, you should submit your run to the main leaderboards and select "Switch" as the console. If the community votes to create separate console boards, then we will move your run over when those boards exist.