Most secret chems shouldn't be secret.

[Flourish]

One option for making secret chems 'less secret' could be allowing you to 'reverse-engineer' samples found in artbeakers for more detailed hints, spend spacebux for a note with a clue, rare half-burnt piles of notes in Z5, etc. That way the chems won't become instantly available to everyone, but it means that you have a hope to learn the  recipes without turbonerding away in chem for hours.

I think having hints to a few recipes hidden in adventure zones could be a cool thing

Good ideas!