Ask HN: Opinions on latest crop of "nootropic" compounds – TrkB agonist etc.?

I know about 5 years ago Scott Alexander did a survey of nootropic compounds and found unsurprisingly that stimulants and caffeine were the only things that moved the needle when it came to learning and cognition.

Now there's a bunch more products going around the biohacking community, some of them research drugs for alheizmers, depression, etc. that are still being tested by pharmas, or stuff from Russian neuroscience.

I won't name specific products, but these are the areas and why they supposedly work:

- TrkB positive allosteric modulators: Boosts BDNF signalling leading to LTP & memory formation; "plasticity"

- PDE4D NAMs: boosts cAMP signaling

- 5-HT4 partial agonist: Fast cAMP/CREB lift for mood & motivation

- AMPA receptor PAM: Rapid attention/focus bump and next-day consolidation

- M1 muscarinic PAM: cholinergic memory enhancement

- A2A receptor inverse agonist: “Caffeine without crash”

- CCK-B receptor antagonist peptide: anti-anxiety peptide

- α7-nAChR co-agonist: Nicotine-like sensory clarity

- non-hallucinogenic 5-HT2A "Psychoplastogens": Ketamine-like synaptic growth minus trip

- NMDA glycine-site PAM: clear thinking without jitters

I consider the classic nootropics (racetams) to be pretty much bunk. Is there any reason to think these might actually work?