I have expertise in ADHD pharmacology:
Bromantane is an extremely atypical substance indeed. It increase dopamine level by a factor of 2 in rodents.
If I remember the main effect of bromantane is via an upregulation of AADC ?
If so (to be verified) then it would mean a (proportionally equal in respect to the base ratios) upregulation of serotonin, histamine and trace amine too since their precursors compete for the same enzyme.

I had read bromantane increase sert but by a factor of 2? That's weird and I doubt that is the case. Hence a better explanation for what is going on would be welcome.
Other interesting aspects of bromantane are the research on it being an actoprotector, indeed a very interesting concept.
There was some research on its anxiolytic properties too?

cons:
it works better in sublingual but sublingual is annoying
bromantane at non-low dose make many people feel slighlty weird, like you know on the background you are on drug. Also this psychological perception is markedly different than feeling being on a phenidate or an amphetamine.
It is likely that bromantane does not significantly increase noradrenaline, which is great since this imply no cardiotoxicity nor vasocontrition however noradrenaline has an important role in fixing ADHD.
It is obvious that bromantane is less effective than vyvanse although it is either an interesting augmentation in parallel or a palliation for those that can't access or tolerate stimulants.
The long terms effects by taking it orally might alleviate the weird feeling though although semi unlikely.

Semax and its modern derivatives are interesting too.
As for modafinil and the more tolerable armodafinil, they have been tested in studies and the efficacy is much lower than stimulants. Contrary to popular belief modafinil 200mg is highly dopaminergic, almost comparable to methlyphenidate 20mg, however the reduced efficacy might be ascribed to either the D1/D2 ratio or the fact it reduce gaba levels or the action on orexins but most likely as in bromantane (although the subjective effects are very different) the lack of potent noradrenaline action.

I have studied every single drug that has been tested for ADHD and the truth is, there aren't many that are promising (except as mere augmentation of a classical stim)
Guanfacine is very complementary.
NRI generally are less effective and cause as much side effects weirdly. Notably nobody knows it but atomotexine is neurotoxic. So if you wanna try one do reboxetine or qelbree.
The interesting thing about NRIs is not that they are NRIs, it is that they act on GIRK https://en.wikipedia.org/wiki/G_protein-coupled_inwardly-rec... and there is a drug selective only on GIRK that shows ADHD efficacy, so this could be a useful replacement or augmentation.

The most potent thing people don't know though is that MAOIs (a, b) have evidence to be possibly as effective as stimulants for ADHD.
See e.g. selegiline reported being as effective as methylphenidate with much less side effects:
https://www.researchgate.net/publication/237845059_Selegilin...
https://www.sciencedirect.com/science/article/abs/pii/009130...
The main unknown with selegiline being if the efficacy works long term or not.
Selegiline is BTW a potent geroprotector increasing lifespan by a very atypical mechanism (shared via the very interesting and underknown drug b-pap) but the main geroprotective effect is obvious: dopamine is oxidated by mao-b and mao-b got the good idea of being collocated to the mitochondria membrane duh
which means dopamin slowly kill you mitochondria which leads to your cell dysfunction and apoptosis.
Now add to the fact that mao-b increase with age..
The only downside with selegiline is that there exist one study showing it can reduce intelligence or at least increase latency in some cognitive tasks on healthy people.
https://pubmed.ncbi.nlm.nih.gov/3927932/
Despite other studies showing cognitive enhancement. also I don't remember if this is the exact study I was refering to.
While selegiline is atypical by not only acting on mao-b (levo-meth metabolites and ppap like potentiation), maois being as effective as methyplhenidate is a consistent finding for all maois tested!
Other mao-b inhibitors like rasagiline and silfenamide have not been tested.
and classical maois while very effective, and actually safe, have non-negligible side effects. However the exist a middle ground, RIMAs.
There exist 2-3 official RIMAs on the market (and many natural ones), one having 2 studies showing positive effect on ADHD for moclobemide.
https://pubmed.ncbi.nlm.nih.gov/1546129/
moclobemide is generally underdosed due to dumb FDA limit while if you watch the tyramine graph 900mg is actually mostly safe diet-free.
moclobemide is remarkable by being one of the drug with the least side effects (except a theorethically worrying rem bound offset of one hour although an effect shared by stimulants too?)
While I expect it to be less effective than methylphenidate, it seems like an excellent augmentation or replacement. with a diet and heart monitoring it can be combined with selegiline or afinils.
So yes as always, the future of the scientific knowledge is in the past (the 90s) and will keep being ignored for eternity except for the very few meta-researchers like me.

The exist many atypical drugs for ADHD, e.g. zinc allow to reduce adderall dose by 1 third, except I would not recommend taking it long term since metals accumulate in the body without chelators, and zinc is linked to oxidative stress (independently of its DRI action?)
Methadoxine is a curious atypical, and is has not been marketed for this use, not because of a lack of efficacy, but because their placebo control was too effective (how tragic and ridiculous)

there are many absurd results too, such as saffron being as effective as methylphenidate..
Pine bark is promising but only works on hyperactive ADHD, not on hypoactive/ADD.
As for mere augmentations, I would look into regular nootropics such as racetams and cholinergics.
The nicotinic GTS can make sense. Also xanthines with longer half lifes and many others.
There are many research stimulants too (ppap, 4-fmph, etc)
I could go on and talk about phosphodiesterases and other topics but this is HN.
Beyond ADHD, consider taking magnesium l-threonate for fighting your synapse losses.
Another underknown topics are the drugs that worsen ADHD such as surprisingly, Inositol.

There are many studies showing potent effects of meditation which is promising although not well specified in how to reproduce.

As a reminder though, vyvanse is the most effective non-polypharmacologic treatment and its patents are expiring in 2023! Unfortunately it is not prescribed in many european countries...