It should be pretty obvious when cranking if the visible spark is weak or strong.

Or visual indicators like this are cheap



I'm more interested that the injectors are firing....to a degree how much fuel they are injecting and that they are firing in sequence.

Just in case something bizarre is happening that they might just be dumping fuel in, or not at all. With OEM rails the injectors are secured in with clips so it should be relatively easy to remove the entire unit for a visual test.