You can find Akkimari Strikers as part of random encounters on a variety if planets. The following planets have a chance of spawning with Akkimari random encounters:
-Mutated/Alien
-Forest
-Jungle
-Scorched

Not every random encounter will have a Striker in it, but keep exploring these planets and you'll find them sooner or later!

How would we manually spawn them?

Sorry about the late reply, but if anyone is trying to still manually spawn them, I found the proper command it's /spawnmonster akkimaristriker