Sure explanations due!
No leash your board is gone away from you at the speed of the river, leash on leg or arm no obstacle no problem , The Spot called Pipeline is a relatively benign spot the water is deep and you are unlikely to hit bottom or obstacle.
My son and I did a river safety and rescue course, where we had a remote safety trainer have a release for your leash on a remote line.
Our training was on a low water day, against this. The exercise was to try and remove your leash on leg, arm, and quick release waist belt.
Leg was absolutely impossible, arm not quite, waist belt stomach strain but movement to release shielded by stomach, rapidly doable.
You only need to release should you get caught!
The catch the wave techniques are three that I’ve seen so far only one involve strong paddling.
That being jumping in upstream of the wave, get sucked into the wave and paddle furiously down the face. Fail get sucked over the back.
Learners get on the wave technique;, stand on the side of the stream on your board, adopt wakesurfing stance and haul yourself hand over hand into the peak of the wave, gain riding stability let go of rope, ride.
The jump technique, works here because the distance from the side to the wave is short.
Technique 1 , jump el prono, leap from side into the sweet spot of the wave with enough momentum to,support pop up. Pop and ride!
Technique 2 The standing ready to ride jump, successful is known as the acid drop, as for previous jump, ensure it is far enough and you carry enough momentum to carry you into power and first turn!
The wave is scathing in its response, a few inches/centimeters out and you are off the back of the wave and down stream.
Rescue techniques can be different and quite specific for the circumstances.
The strength of the flow determines the sort of weight you have to work against for a self rescue or pull someone against if they are held against an obstacle. Say a 75 kg 180 cm person in a 2metres per second stream = 40 kg and 3 meters per second stream 93 kg a 4 meter per second stream 176 kg.
Surfboards against a rock, unbelievable up to 500+ kgs try hauling that or yourself out, so quick release great idea.
The safety course was two days one night theory two days practical, serious fun. Exciting with danger
People have died doing the course!

I've taken up troll hunting just for fun, instead of a rifle I'll just use a pun! 冲浪爷爷