I'm not familiar with "pond pumps", but have lots of experience with sump pumps. If it were me, and I was using this near 120v access, then I would go with a sump pump such as this:
https://www.amazon.com/Superior-Pum...bmersible/dp/B000X07GQS/?tag=treasurenet01-20
It pumps up to 2400GPH, is small, energy efficient, etc. I've purchased two pumps from this manufacturer and will tell you this much - I will never again pay the over-inflated price for Wayne pumps!! This brand is awesome! VERY quiet! Also, there is a GFI adapter you can get for outlets that are not GFCI. You have a choice of replacing a breaker to your work area with a GFCI breaker, replacing just an outlet on a non-GFCI circuit, or adding a GFI unit such as an adapter or a short extension/adapter. Several different choices can be found here:
https://www.amazon.com/s/?tag=treasurenet01-20
If possible, it would be best to change out a non-GFCI breaker for a GFCI breaker. Reason is, GFCI outlets will often trip off even if you do not reach their rated capacity. I would imagine the adapters/extension adapters would be similar. Also, my experiences with these go back many years ago. They may have improved in the past 10 years. Still, I promise you that GFCI breaker would be the overall safest and surest and most reliable route!
As for flow control, you could use PVC pipe and install a valve. Here I'd recommend a 1/4-turn valve, or maybe even an older valve that requires several complete revolutions to go full-on to full-off. 1/4-turn would be easier to mark, but more difficult to fine tune, whereas the other valve would be much easier to fine tune, if you can keep track of the revolutions. I especially like Kenmitch's idea of using a diverter valve, as that way you're keeping full flow through the pump, which it's the water flow that keeps these pumps cool. I don't know how the pond pump is cooled. Looks like it "might" be air cooled, or maybe uses a hybrid cooling system.
Keep in mind that if you use a 12v pump, the more water you move, the more amperage you draw and the quicker your battery drains. I recently bought a new battery charger that, upon initial impression, I had my doubts on. But after using it, I'm thoroughly impressed. I only wish they hadn't made the cover to house the cables, as the extra bulk makes it more difficult to position for closing the hood when temps are -30° or colder.
https://www.amazon.com/gp/product/B000BQSIWK/?tag=treasurenet01-20