Is this a standard crank arm/spindle bolt, or something unique?

I would like to add this exact type of fastener to my Maxy Cross cranks. Help please!

that just looks like a standard 8x1mm buttonhead "hardware store/fastener supply" type bolt and perhaps a fender washer. doesn't look like anything "bicycle specific/sourced".

Yeah, I guess so. For some reason I had it stuck in my head that it was a 1-piece fastener...kinda of a custom thing or proprietary. Not as sexy as what I had in my mind, but certainly a lot easier to do. Thanks!

Looks similar to the old Shimano Dura-Ace 1 Key Release bolt. No crank puller needed.