[peteradio]

Not sure if the throat is large enough but a portable electric bandsaw would be able to chew through the unistrut steel and in the jobs I've used them on they are precise enough.

[samtho]

Portable electric bandsaw is the tool of choice for most electricians who use Unistrut.

[lazide]

An angle grinder with a cutoff wheel similarly has no issues.

It can be a fire/noise/dust hazard, you wouldn’t want to do it in a grassy field or server room, but for any construction site it’s easy peasy.