I can't speak for Phenibut, but I can speak for Kratom. Though they both seem to target the same brain receptors to create a similar effect...
So you have your low doses, where it's like an off-label ADHD stimulant. So if you've ever tried Modafinil or dextroamphetamine (Vyvanse/Adderall) it's close to a lower dose of something like that. Think 20-30mg without titrating. It's a low-key buzz that (to me) is like a shot of espresso at 2:00 in the afternoon. Not enough to get you buzzed, but just enough to get you through the day. If you're a drinker though, you might want to take a higher dose, since then it changes it's effect a bit and starts to act like kavalactone (kava root) but without the risk of liver damage. Personally, higher doses have more muscle-relaxant effects, something indica-like I suppose... But if you're driving or using machinery to any significant degree in your day-to-day I wouldn't be taking anything more than 8-15g of it, just for the sake of your personal safety if that at-all matters to you.
The only real gripe that I have with Kratom as it stands, is your propensity to get addicted to it. In terms of it's addictive potential alone I'd probably say it's a bit less than what you'd see with Percocets. Sure, you can pop a few recreationally now and again, but daily use probably means you're going to develop a problem. Mitragynine, the active compound in kratom (and this is anecdotal evidence) will give you similar withdrawal effects to Muscimol, the compound found in Amanita mushrooms, according to my own experiences with it. Withdrawal is NOT fun, and I think that transitioning to Kratom as an alcoholic is NOT a good idea, but I won't leave you without something actionable either.
If you're an addict and you're substituting your habit with another addictive substance, you'll never kick the habit. What I can recommend though, are two remedies that are legal (the latter depending on the state) that I think you'll have better success with. The first being Arecoline. This is a minor stimulant that acts similar to nicotine, but is leaps and bounds less addictive. It isn't classified as a controlled substance federally, and can be found in Indian/south Asian grocery stores in the form of the Betel Nut. I'm pretty sure you can also order it online or off Etsy as well. For depressants, I would push you towards CBD tinctures; something with low THC but still relaxes you in the same way alcohol might, so that you can kick the habit without substituting it for something else.