I was thinking about how it could actually work like this: You can get quirk fruit from quirk users and the users like a tree growing fruit was would grow back their quirk in a few days or however long yoi think it would we require. For people who eat the fruit they'd have the quirk for a limited time before the fruit is ingested and leaves the body, the quirk also leaving the person. Just an idea.
It probably work better for a pro-hero then using it on a student due to where he would get the quirk fruit. Depending on how long it takes for a quirk to come back the other students wont be willing to hand over their quirks and I dont feel like the school will just bring in villains for him to just get quirk fruit.
The pro-hero could get donations from people to give him quirk fruit and something that could be cool is that he could have like a collection of quirk fruit from villains he bought in. Like a trophy room. Or she, could be a she. Again just another idea.
Again, great ideas! I love the lines of thought! But I'm thinking more along the lines of 'the more powerful the Quirk, the longer it takes for the fruit to grow back' And since each tree would probably hold at least....I dunno, 5 to maybe 10 fruit at least, there's plenty to go around. Of course, the detail remains...how do I get the Quirk from another user to manifest into a tree?