I’ll call this geometrynodes fire destruction effect final now! 
In the video I’m explaining the basic logic of how it’s done.
And here’s the video:
It might be interesting to note a workaround I found doing this. The problem was that the falling pieces produced dotted fire and smoke. That happens because sampling substeps don’t work with modifiers.
How I worked around this was like this: I simulate everything (cloth, fire) in half the time, but then only render every 2nd frame. That way I fake having a ‘substep’ between the frames and the dotted fires of the falling pieces mostly disappear. Obviously, you could increase the same workflow and simulate at, say, a quarter of the speed, to then only render every fourth frame.
One thing I haven’t found a way to do so far has to do with the pieces that fall down but then bounce back up again. That happens because they’re half-pinned (weight 0.5 or something). One way I thought might work (but doesn’t) is to have a geometry nodes taking as an input a vertex group and outputing it to the same vertexgroup. But it doesn’t persist. If it did, you could add e.g. “0.1” everytime the geometry nodes are evaluated to all vertices that have a weight above 0.001 - that way all vertices that are slightly affected by the effect eventually become 1. But anyway, I haven’t found a way to do that (I’m aware you could use the frame number, but that’d grow simultaneously for all vertices).
At any rate, if you’re interested, on Gumroad you can get a detailed tutorial & the source file: https://marcchehab.gumroad.com/l/epicfiredestruction