Interesting thread.
I've not been bike camping for at least 20 years, but the two decades before that was spent doing it a lot. I was just thinking of the kit I still have, stashed away and unused since. I'm still up for it, but not in the cold, not any longer.
For cooking, I used an assortment of devices, from pump-up paraffin (kerosene) stoves to the ubiquitous Gaz (in Europe) small disposable cartridge stove, but I ended up settling on these two...
For solo camping, a Trangia meths burner and two billy cans...
And for emergency fall-back, the hexamine stove, as beloved and hated in equal measure by countless services personnel around the world...
Both take up no space at all, and neither has ever let me down.