To be honest, I'm only speculating... But if you got the conditions in your cabinet dialed in properly, and you grew two 4ft tall plants, LST'd... you could easily yield a half pound in there, depending on the strain.... Some plants buds are denser & heavier than others.
Like I said, that's speculation and I'm not guaranteeing anything...
You've got a ways to go before you get yields like that.
It is definitely possible though!