Any advice for updating from 1912 CU0 to 2402 CU1? My plan is to first update to 1912 CU10, then to 2203 CU6, and finally to 2402 CU1. I’m not sure if the target devices will survive two major upgrades, so I’m considering booting all VDAs from the corresponding major release beforehand.

I would just reverse image personally, but you should be able to jump directly to 2404 cu2 without any steps.