I don't know of any better explanation than thermate (related to thermite, also has sulfur to lower melting point of steel/iron).
7 is a smoking gun, but restricting focus to 1&2 I think the smoking gun is molten steel
Responders & structural engineers reported molten steel in the rubble
https://youtu.be/fs_ogSbQFbM?si=r2TfuT70Otk_DW1b
Molten steel fused with concrete was recovered from the rubble; it's rusted brown so it's almost certainly iron/steel, not aluminum or lead
(21:20)
https://youtu.be/bObrsLtlmrY?si=ILROSGmnRPTEUVrm
Jet fuel can't melt steel, as the fire engineer at 37:30 will tell you, and any weakening in steel occurs very gradually.
https://youtu.be/DgwlFY-4Txc?si=DdZcFQYD0Dm9btGh
The official pancake theory as detailed in that last link can't explain the molten steel, and IMO doesn't explain the sudden collapse of the whole structure.