@twobob: much too complicated for end users
. Everything "ota2" supports multiple devices, so should be done like that (with the exception that you can't mix k4 and k5). But essentially, it's enough to provide ONE file for ALL Touch/Paperwhite users, and one file for all K4 users. Check the devcerts or "rescue pack" files that I published for Touch devices for examples
Matters are different for the K3 ("ota"), where each device needs its own installer... at least AFAIK.
See the attached sources, and it should be pretty clear.