Just seen you don’t have access to a heating element - sorry! That makes much of the above void. Can you make use of an alcohol stove? Buy some denatured alcohol (meths, bio ethanol, methylated spirits etc) and a drinks can, with which you can make an alcohol stove that can be used to boil water and make other simple meals. But be very careful with alcohol stoves they burn with a very dim flame which can make it very hard to see, which can be very dangerous if you spill lit fuel. Take adequate precautions. Also usual notes about burning things - try not to do it indoors, make sure you have adequate ventilation, keep away from children, have plan for extinguishing the flame in an emergency etc.

Basic pop can stove

A safer version that should be more spill proof, I’ve made something similar using graphite felt from a welders blanket before.

YouTube link to a graphite stove burner.