How can I run Nema23 @ 2or3 rpm

I have a spare Nema 23 & M335 driver which I would like to be able to run at very low variable speeds for a non CNC project.
Is there an easy way to achieve this? Potentiometer maybe? Or am I being naively hopeful.
Thanks

Something like this would work
https://www.ebay.com/itm/31350853875...Cclp%3A2334524

Here is another one that will work:

https://www.ebay.com/itm/294216615395

Problem is, these boards may have too wide of a speed range for you. At the lowest setting, the speed will change from 1.5RPM to 45RPM (80Hz to 2400Hz).

Thanks Jim