As the title implies, I’d like to start streaming Mario Maker 2 speedruns. However, my computer is a tad slow and I’d rather just use clips from the VOD that would be posted to YouTube as verification. Will the fact that I am outputting game audio and my own commentary be an issue?

Hi. As long as your clips show the complete run without interruption, it's fine. Lots of people submit recordings of live-streamed speedruns with face cams and voice-overs. Good luck!