What Dave said.
IDK if any alternatives are worthwhile in this case.
If I had to try something to avoid solvents it would probably be createx clear or floor care but splash is already solvents so....idk
Splash recommends the 2k clear;
"Splash Paints LLC offers a variety of factory color matched paints ready for airbrush! When dried, they dry completely flat due to its leveling characteristics. Our pearl/metallic flake sizes are carefully considered to match the scale models. All of our color paints are solvent based lacquer. Our primers and clear coats are only available in 2K Urethane for best durability and results."
If youre using a 2k other than splash/airbrush intended clear be ready to over reduce by a lot. Like in the neighborhood of eg; 3:1:1 clear could become 3:1:4 If you dont want to bury your panel lines.
Not sure anything is going to be able to be cleaned sans tools... some disposable type like these ;
https://www.harborfreight.com/quick-change-airbrush-kit-93506.html
Which is all i'd add to Daves list. They spray well, and for $2 a session you just throw away the bottle, nozzle and all, no cleaning. I use them for small touch ups on real cars sometimes, its cheaper than cleaning a detail gun. Though the "paint fenders ,bumpers and doorjambs" on the page there I have to laugh at
.