Functional GABA cannot be 'donated' via oral supplementation, which can't cross the BBB. And benzos dont really modify GABA, they render it redundant and pretty much shut down your natural production, which is in large part what causes the awful withdrawal symptoms that many members here have suffered.
When the Ativan or Xanax or Valium is stopped, the system generally can't just pick up the slack and go on as before. The roads and bridges have all been torn down, along with the transmiting towers adn receiving terminals. So until your system can rebuild those, which is a pretty long, arduous, and for the patient, unpleasant process, you're going to be one raw, bleeding, jangling set of nerve endings all screaming for relief.
There are multiple GABA sites in the body, so there may be some relief provided by the GABA receptors in, say, your gut or your liver, but it would be minimal, and as far as I can recall, those sites wouldnt cross the BBB either ....
I believe that the Source Naturals product has other substances in it to boost its effect. Forgive me for not looking it up, but pretty weary and wrung out right now.
I researched this and found citations on PubMed that state it can pass the BBB*. I think we discussed this before. The risk (spending < $15) to reward (helping a horrible disease) has a great metric. The difference with this is that it is sublingual which means absorption is greater than oral supplements.
*As you know, any argument can be presented to support their viewpoint. The best determinant is experience, either 1/ something works 2/ caused problems or 3/ neutral effect. I only look at research papers as new ideas to try and not definitive unless it provides some heavy cautions.