I wanted to ask if I can submit a game request in multiple videos because the speed run I have to do is much longer than YouTube or twitch will be able upload in one pice I think.

That should be fine. I don't believe there's a way to link multiple runs directly so you will probably want to link one in the run section and put the rest in the additional details section.

Longer than YouTube can handle you say? https://www.adweek.com/performance-marketing/longest-youtube-video/

Out of curiosity, which game and category would that be? Runs that are longer than 12h (youtube: https://support.google.com/youtube/answer/71673) or 48h (twitch), are relatively rare.

If i am not mistaken a pure basic YT channel can only post 30min vids (or mabye 15), but there is a way to activate the longer uploads,