Instead of getting One For All, what do you think Deku's natrual quirk would be? Comment below how you would combine Hisashi's firebreathing and Inko's levitation into one quirk. If you want to be more creative freedom in your version, you could have a rare mutation, like with Eri's Rewind.
Plasma Jet - Deku can mentally project flame-like green plamsa from any surface within a 30 metre radius. He's unable to manipulate the shape or temperature of the plasma, only being mildly warm. The plasma exclusively forms into thin and narrow beams, like a blow torch.
The main benefit to the Plasma beams are the backwards momentum they create. If placed correctly on an object, Deku make it hover with the same method of a jetpack. He can place those plasma beams on himself: Giving him flight and increasing speed/power (Same way Iida's engine allows).
Deku can control either one powerful plasma beam or numerous weaker ones. Attempting to create too many or increasing their power too much, can cause mental strain and possible headaches. His personal records so far: The maximum number he's created is of 24. The tallest single beam he's created is 10 metres, with momentum that can destroy a break wall.
If you want to visualize it, here's a drawing I made on on Google Slides. Please exuse the stick men, I'm not an artiest, as you'll see: