I thought just now that maybe we can do a PICO-8 speedrun catagory from the version of it inside Celeste

The game itself has its own leaderboard https://www.speedrun.com/celestep8 (in which the Celeste version of it is allowed). If you mean a run involving unlocking it in this game and completing it, that has its own issues in that there isn't really a good way to time it and if you want to play PICO you should probably just play the game on its own.