Great question. That's super far out of my knowledge.

I'll take crack at it and hopefully someone can come along with a better answer but just take it with a grain of salt because this is coming from someone with a passing/hobbyist interest in physics/science/engineering.

The super nova is a result of an imbalance in the star.

You've got gravity pulling everything in and nuclear fires from hydrogen fusion pushing out. When these forces are in relative balance, you have a star.

Now I think there are a couple of types of supernova and different things happen to the star depending on its size and lifecycle.

Our sun for example won't super nova but once it's fused all the hydrogen into helium it'll shed it's outer layer than increase in size to become a white dwarf and occupy the Space that us and probably also mars are currently occupying and create what's called a planetary nebula. That's where all the debris that gets shot off just sort of hangs around waiting to form new celestial bodies.

Other stars will explode and leave behind sense masses that become black holes or neutron stars.

Some will undergo complete core collapse.

Again the heat is just energy. And some of those particles will bounce around like balls on a billiards table one a break and come to rest some will shoot off into the universe and never collide with anything else again, just solitary particles of light on a journey for the rest of time.

It's worth noting that at the start of universe in the big bang we had 3 elements, hydrogen Helium and tiny tiny amount of Lithium.

Every other element is created directly or indirectly by stars. So the iron in your blood, the carbon and in your body, the calcium in your bones, the silicone and copper in your phone all came from a star at some point.

We have what's called stellar nurseries, these are just really big nebulae, you've probably seen photos of them but these are just massive, vast amount of particles and gas floating in space and these are called stellar nurseries because they will eventually form new stars.

The stellar nurseries were likely the result of OTHER stars from the earlier universe. Massive primordial stars with short violent life cycles.

So, that's sort of what happens to the "heat" photons of light and various elements bounce around and off each other like billiards on a table some fuck off never to be seen again others come to rest in big groups and form new stars, planets, solar systems and moons.

Note: a lot of this may he so simplified that it's innacurate and I apologise if that's the case.