Has anybody done this and taken a recording? I'd love to watch it. I'm assuming Ebe for every race? Seems like a Domirae/beandip/Brado kinda job.

We have a category for All Tracks done with 1 character found here:
https://www.speedrun.com/swe1r/full_game#All_Tracks_NG_One_Character

Metallica has a run with No Upgrades anakin, who is a starter pod:
https://www.speedrun.com/swe1r/run/y952n9kz

To add to what goofbrush said, I just think that 100% isn't particularly interesting under these conditions. The appeal of the category precisely is the fact that you have to switch between different characters, even without skips or upgrades. If you want to see specific characters having to go through everything, All Tracks NG+ with one character is the best choice, since in that category, you can use any character you want, not only the ones available at the start of a savefile.