Appears to be a long-known long-studied topic in two part finishes, especially automotive.
What I can find of the isocyanates is potential or probably carcinogen, but perhaps falsely attributed in one of the animal studies because of toluene presence.
But spray outside only. I vaguely recall spraying my car hood in the driveway (but with the garage door open), and when nobody was home (to avoid grief with the mrs). Amazed at the hardness and toughness of the finish, though, and it looks like there are "ISO-Free" 2k finishes, but not in cans.
No interest in dealing with the stuff for small projects in a gun that would need to be cleaned. Until it's warm out, I'll be using shellac on guitar bodies, anyway. It doesn't care that the back end of the shop is 45 degrees.