This is the pump I ended up buying, and it is amazing. Freein Triple Action Hand Pump
The triple action works great, easy to use, and makes pumping very fast.
In combination with this Ryobi 18V Inflator I can inflate the paddle board in record time. I let the Ryobi 18V battery powered inflator fill the board with air, and then start at stage 2 of the triple action pump. The Ryobi 18V inflator is also good for quickly deflating the board. It will suck all the air out quickly, so you don't have to wait, or roll up slowly.
If I don't have the Ryobi 18V inflator, then I just start out with the Freein triple action pump at stage 1, which is way faster to fill the board than the stock pump.
The pump that came with my Saturn SUP takes forever to pump up the board. It's a work out, which I don't mind, but the amount of time it takes is annoying. I'd rather be out on the water than pumping up the board.
Sure you can find some electric pumps, but they are expensive, loud and require a power source. Either they are connected to 12V auto outlet, or battery powered. All this increase in complexity makes it more likely to break down, not be charged, or batteries gone bad. It's one more thing to mess with that I would rather just do by hand.
Some of the higher volume pumps rival the cost of an electric pump
ITIWIT Stand Up Paddle Triple Action High-Pressure Hand Pump
These are the highest volume and fastest hand pumps available. Looks like they were introduced sometime in 2017, so fairly new tech as of my research. The only thing I don't like about this pump is the price, right around $100. You can buy a good electric 12V pump for that, and hook it up to some cordless drill batteries.
It has 3 modes that you switch as pumping gets more difficult:
Double cylinder, double action - 3.5L for each stroke - 7L for one stroke cycle (down and up)
Double cylinder, single action - 3.5L for one stroke cycle
Single cylinder, single action - 1.75L per stroke cycle
This pump is relabled by many different SUP sellers. The best way to search for it is to use these terms "Triple Action SUP Pump"
Airhead MOAP Pump
UPDATE: I purchased and tested this pump, but was not happy with the results. Maybe I got a dud, but the piston was always pushing back up, like a one way valve was broken. I returned it and didn't try another, as I thought this was not a good sign of quality.
This is the second largest pump I have found. It's volume is 4.7L but it is only a single action pump with a switchable smaller cylinder for higher pressure pumping. If this pump were dual action, it could be an awesome pump, and would be even quicker than the triple action SUP pump.
Combining a hand pump and an electric pump
The most time consuming part of pumping up the SUP is simply inflating it to 1-2psi. A high volume electric pump could do this quickly, and then you can continue to pump by hand to pressurize the board.
Ryobi sells a 18V cordless high volume pump designed for air beds and other low pressure inflatables. I like this because I already have Ryobi 18V power tools and lots of batteries. This could be used to do the initial inflation, and then take over with the hand pump to bring it up to final pressure.
T connector for dual pumps