Ah, I actually don't recommend the NOW brand of Rhodiola. It's not bad, but it's just not that very good. It seems to be missing something, I can't tell what, but there's definitely something that's lacking.
I recommend you try nootropics depot rhodiola. They have the 3% rosavins version and the 3% salidroside version. The latter is more calming while the former is more stimulating.
Two other good brands are LIfe Extension and Solgar.
Rhodiola is one of those herbs that has different effects depending on the brand.
Regarding the microdose LSD, thanks for linking that study, never seen it before. But yeah microdosing LSD is quite popular for cognitive enhancement. In fact, people in the Silicon Valley regularly use it.
Really, anything that alters perception is bound to improve some aspects of cognition, especially creativity. This is because the mind's default mode network stops influencing consciousness as much as it usually does. Basically seeing things in a new way let's you realize things you previously couldn't.
Unfortunately, LSD still remains illegal so it's hard to experiment with. But, THC is now legal in many parts of the US and in Canada. Have you tried microdosing THC? It helps restore some aspects of cognition, at least in older mice: https://www.nature.com/articles/nm.4311
Also, I have to ask, are you the John Shirley? As in the author and musician?