I think some water based finishes like target are far more benign, but then others like the enduro 2 part finish that has a good reputation is isocyanate.
I've had good luck with crosslinked target and have never pushed it to see how scratch resistant it is. There's a gigantic difference between it with and without crosslinker.
The enduro finishes that are toxic appear to have some comment on them about being for professional users.
Not sure about conversion varnishes, but if bill is spraying them, I'm assuming they don't have isocyanates in them.
The initial draw for me in all of this is the fabulous performance of the spraymax 2k can product. Only spraying a guitar, i could buy one can for $18, build a finish on the guitar, buff it back and be done. Throw away the can, no clean up, etc.
On bigger projects, the cans would become a problem, but I already either wipe/brush/polish with shellac on those or shellac seal (for color) and then spray clear target WB over that. The sale of that 2k can stuff doesn't adequately warn of its dangers as I'd been warned either in comments or in forums and did the spraying outside of the garage and with a well-fitting OV mask, but it sounds like that's minimalist effort for it.
My regular spray and polish/brush options are OK, and they look like they're the appropriate options unless i want to go up in toxicity or use more spray equipment (and have to clean it).