Above experiences might have to do with dopamine more than anything. AFAIK the dopamine system is very malleable and adjusts itself easily, hence e.g. why a lot of people who take prescription stimulants feel "oh wow" for a few days or weeks then become disappointed (but also why low dose prescription stims are rather harmless and unproblematic to start/stop as the brain easily adjusts and one might simply feel a bit excessively tired/wired for a short period).
Either way I suspect that's what most of the popular "test boosters" do is give a sense of energy that perhaps has little to do with testosterone, just my guess. Things that vaguely speaking are "dopaminergic" (i.e. vaguely stimulating, everything from dexamphetamine, ginseng, to fulvic acid) seem to have a rather simple and easy relationship with mood-lifting properties (including horniness etc, "high test" feeling), you can take it and you immediately feel a lift. I'm not so sure the same is true even of injecting massive amounts of testosterone, sex hormones seem a bit complicated either way... I don't really know what fulvic acid does tho, but I doubt it raises testosterone very much.