I've been watching the colosseum videos a lot recently and I just realized that Bellamy's quirk allows him to stretch his body parts and shoot them out with more force. But isn't that just what the Gomu Gomu fruit does?
Luffy's version allows him not to only stretch his body and shoot them out with more force, but he could inflate them and absorb damage.
So in a sense Bellamy's quirk is a weaker version of the gomu gomu fruit