For years dive agencies ran, and continue to run, programs at resorts where you spent an hour in the pool and then went scuba diving for the day. They are called "resort dives" or "discover scuba" or other such things. You paid for an hour in a pool perhaps and then went out for a dive with a Dive Master or Instructor. It usually was a one shot experience or required to do the training again.
Our SSI program is called Basic Diver and the process is much the same, only you get a dive certification card that is good for six (6) months. No needing to repeat the course. You still must dive with a dive pro and are limited to 40 feet on your open water dives, but this gives you the opportunity to dive several times while on a cruise vacation, or dive you time to do the training here at home, and then weeks or months later when you take that trip dive with a SSI operator.
It requires a afternoon of approximately 4 hours in our pool and one open water dive when we go to Santa Rosa NM or Balmorhea State Park on a weekend.