I did a high-level exploration of the field a few years ago. It was rushed and optimized more for getting it out there than rigor and comprehensiveness, but hopefully still a decent starting point.

I personally think you'd wanna first look at the dozens of molecules known to improve one or another aspect of cognition in diseases (e.g. Alzheimer's and schizophrenia), that were never investigated for mind enhancement in healthy adults.

Given that some of these show very promising effects (and are often literally approved for cognitive enhancement in diseased populations), given that many of the best molecules we have right now were initially also just approved for some pathology (e.g. methylphenidate, amphetamine, modafinil), and given that there is no incentive for the pharmaceutical industry to conduct clinical trials on healthy people (FDA etc. do not recognize healthy enhancement as a valid indication), there seems to even be a sort of overhang of promising molecule candidates that were just never rigorously tested for healthy adult cognitive enhancement.

https://forum.effectivealtruism.org/posts/hGY3eErGzEef7Ck64/mind-enhancement-cause-exploration

Appendix C includes a list of 'almost deployable' candidates:

Amantadine, Amisulpride, Amphetamine (incl. dexamphetamine, levoamphetamine) Aripiprazole. Armodafinil, Atomoxetine, Brexiprazole, Bupropion Carbidopa-levodopa, Clonidine, Desvenlaflaxine, Donepezil, Duloxetine, Entacapone, Folic acid, Galantamine, Gingko Biloba, Guanfacine, Istradefylline, Ketamine, Lisdexamphetamine, Memantine, Methamphetamine, Methylphenidate (incl. dexmethylphenidate), Modafinil, Opicapone, Piracetam, Pitolisant, Pramipexole, Rasagiline, Reboxetine, Rivastigmine, Ropinirole, Rotigotine, Safinamide, Selegiline, Sodium oxybate, Tacrine, Tolcapone, Venlafaxine, Viloxazine, Vortioxetine

I'm a broke student but I donated what I could muster right now, intending to donate more in the future.

LessWrong is without a doubt worth more to me and to the world than what I can currently pay!

(Commenting because it might marginally increase probability of other people donating as well!)