How to use a specific keyboard layout upon boot?

I've installed DosDude's patches to get Catalina running on my Mac Pro 4,1. However, I'm a Dvorak typist, and now I find I'm booting Catalina in "Canadian English" layout instead of Dvorak. So I have to struggle to type in my password! After I log in, I do have the Dvorak layout. I thought this was in NVRAM, but the only interesting output from "nvram -p" is "prev-lang:kbd" which is set to "en:16300", which is exactly what you'd want for Dvorak . So, how can I boot Catalina and have it come up in Dvorak layout?