Apart from making commercial energy effectively unlimited,
It would make fusion easier, but pure protium-protium fusion is moderated by the decay of diprotons into deuterium which is moderated by the weak force. Diprotons are unstable and will rapidly fission back into a pair of protons again, and the decay into deuterium is rare. This is one reason behind the very long lifetimes of hydrogen burning stars (protium fusion is slow) vs the much shorter lifetime of stars which fuse helium and heavier elements (because they don't have to wait for a slow and unlikely decay process).
does this technology... break the laws of physics/break the universe in unexpected or undesirable ways?
If you have a pair of protons, and you magically tunnel them together into a diproton, they'll probably just fission again. They'll fly apart with great rapidity, because the electromagnetic force is strong and they have like charges. There's a lot of energy released in that repulsion. Where'd it come from?
Even if you couldn't induce fusion any faster, if you get more energy from the repulsion than you put into the tunneling, you've created a perpetual motion machine with all the catastrophic thermodynamic badness that implies. If you don't get more energy out than you put in, then I'm not sure you've made fusion any easier for yourself.
On further reflection it occurs to me that if you had a magical way to get nuclei to fuse that didn't give you free energy, it could in fact still be very useful.
Very hot fusion plasmas suffer from Bremsstrahlung cooling where x-rays escaping from the plasma take away a substantial portion of the energy released by fusion. p-B11 fusion is particularly afflicted by this problem. If you could fuse a cold plasma then your fusor could be a lot more efficient, and need fewer bits of awkward tech like x-ray voltaics.
The energy cost of running your magic fusor might bring the Q-factor down, but if more of the energy of the reaction could be captured (because it is in a more convenient form, like fast charged particles) then the actual energy output of the reactor will be higher than for a hot fusor.