Pipa can easily create expressive fast strumming which would normally take time to create manually, and is not really possible with a midi keyboard. Create a looped velocity sequence for the strum, include some randomization and use the ADSR to ease in and out of the strum.
On the left, set the length of the velocity sequence for the strum to loop through, set the levels, and introduce randomization.
In the middle, set the speed in ms or sync time and turn the device on or off using the switch or button.
On the right set the ADSR. This will attenuate the velocity level so you can create expressive easing in and out of the strum.