I would research the device more, i couldnt find to much information on it, but from what ive read the m7m algo goes off the cache in the processor and mining actually uses very little memory hence why its possible on pi's, i doubt its impossible to get one to mine xmg but you would probably have to write your own miner or heavily modify one of the current ones to run on the xtensia 32bit processor and would expect 0.5h's, and it depends which version the esp32 uses, when looking on the xtensia chip each one is customised to the manufacturers specifications. It's all open source so you can see all the code at https://github.com/magi-project/magi. I think the xtensia chip could actually be quite use full to mine xmg and aeon when looking on the custom order section for the chips, but for someone who is prepared to custom order 100+ chips and build their own usb or asic type miner.