What happens when the resulting meson collide with other nucleons, do the muons transfer momentum to other nucleons, or do they fuse into other particles. I was wondering if there is any way to harvest energy by charged particles instead of heat.
Negative muons could replace electrons when colliding.
This is what happens with muon catalyzed D-D fusion.
Simplified explanation by this youtube video.
Harvesting highly energetic charged particle energy can be done by guiding them through the centre of toroidal coils.
I recommend you to read Leif Holmlid's papers, in particular his publications after 2014.