Exactly my thought. Serotonin is also weird to put on there, omega fat oils have - I think - not conclusively been proven to help (big junk science study on kids in UK, IIRC), 2M2B is again indeed an anxiolytic but that is not the same as a nootropic. Diphenhydramine also isn't one that I know of, if anything it potentially royally fucks your cognition. Propanolol as a beta-blocker can enhance some types of performance but indirectly, hardly counts. Why it doesn't really count is illustrated by anxiolytics that don't only promote tranquility but also allow sedation to make you less sharp. (Likewise not all euphoric drugs can be listed as anti-depressants, that kind of thinking is incredibly myopic. Which might suggest you are taking lobotomizing agents substituted for actual nootropics

hehe j/k)
I don't consider phenibut a nootropic either though some do. Picamilon (not listed tho) is also a GABA-drug but like theanine it is not sedating and the calm is subtle because of that. Picamilon might be one I would almost have doubts about.
Haloperidol? Fucking lol!
Probiotics? I don't see how, do you have bowel movements in your brain?
L-arginine, nah not really. Is supposed to be mildly vasodilatory though - and helps with other things. All of those like tyrosine , etc that are remotely or not so remotely involved in anabolism of neurotransmitters can be useful if you are running low... but other than that I don't see how they would matter significantly.
Problem with GABAergics is: GABA α5 agonism (the α5 subunit is found in GABA
A receptors) eventually interferes with memory formation which is imperative in cognitive processes. Attention and focus involve memory to a large degree, think about it! Learning using attention requires keeping enough information in your working memory at the same time to combine it via association and manipulation for example, into new understanding. If you wiki nootropics you will see that there are memory improving nootropics that are inverse agonists on that sort of GABA receptor.
By the way phenibut happens to work on GABA
B so the memory story doesn't entirely apply there.
I would add to that nootropics list:
- phosphatidylserine (tried it and found it noticeable - can't say that about all nootropics or supplements - and a success)
- modafinil (obviously, adrafinil is on the list and it's a pro-drug for it)
- selank
- semax / semaks (I want to try these latter two but I'm just not made of 100 dollar bills)
- IDRA-21 (is for sale actually), ampakine
- noopept
DMAA, would not recommend that - never taking that again.