Best way to upgrade Windows 10 Home to Windows 11 Pro and have install stick for future installs ?

Hello. Forgive my ignorance, but I have some questions regarding how best to go about this.

Gods willing, I want to upgrade from 10 home to 11 pro without having to do a clean install. However, I also want to have installation media so if I need to do a clean install at a later date, I don't have to install Windows 10 again, THEN upgrade again.

I'm not sure if I should buy a copy of 11 pro and install that over my 10 install (assuming that will even work without wiping my data) or if I should do it via the windows update process and then upgrade to pro after. If I do the latter, how does that work for licensing for the future? I THINK there is a tool somewhere on MS site where you can create a windows 11 install USB, but what do you plug in for the license key if you are doing a clean install after having upgraded from 10 via windows update? Your old windows 10 key?