regarding your edit there, I guess most people stopped reading at 'essential oils' without knowing where this was going.
this is one (the only?) actual medical use for these things - their main thing is that they smell in a certain way that is consistent, so you use them to retrain your sense of smell. that's it. no taking internally or applying to skin or whatever. just take the stopper off the wee bottle, sniff and repeat for as many bottles as you can be arsed.
when I had covid-19, I didn't have so well defined scents on hand, but I did have several colognes I could sniff, and I knew fairly well how they were supposed to smell and could use those to gauge my senses. fun times, they were...
Loving the goblin fermentation vibes you re giving off there. Never stop.
Mostly beer brewer here, so dumb things I've done were mostly process related. Fermenting beer with unsanitized wood chips - turned sour. Adding too much rye or pumpkin - took me 12 hours to get the damn thing made - stuck mash.
Fermentation wise, not brewing, messed around with some koji with varying degrees of success.
If you're doing things like spam alcohol, have you also considered miso as an ingredient?