Although Pixel Worlds isn’t listed on www.speedrun.com, quite a few people have already done and uploaded Pixel Worlds speedruns to YouTube, including Jake himself, so there’s definitely a community for it, a niche one at that though.
The most common type of speedrunning within the community at the moment is speedrunning to X amount of world locks, but you could always come up with some interesting new categories for the community to compete in.
I did that like a year ago. No believe go on the discord and look it up. Last year before all those speedrun wl vids I did it 3 TIMES before the first vid camew out