Phenibut - Can it help with PMO cravings or make it worse?

It will 100% make it way way worse. Phenibut makes you horny as hell. It's very hard to take it and not deal with the arousal you experience in one way or another. If you're taking it with your partner, then that's one thing - but if you're taking it alone, you will absolutely have a much harder time not getting off.

Of course it's plenty possible to resist, but it's 50x harder than when sober that's for sure.

I also honestly don't recommend taking Phenibut for anxiety. Phenibut really needs to be spaced a week or two between doses to avoid tolerance build up. Taken more frequently you'll start to get rebound or even full blown withdrawals, and GABAergic withdrawal is not something you want to mess with. It can be a fun social lubricant similar to alcohol if you use it once in a while in moderation, but using it to self-medicate sounds like a recipe for disaster.