@Pompous Git - Re: ?
Only Ubuntu, Fedora and perhaps OpenSUSE work with SecureBoot because they have Microsoft's blessing. All other versions of Linux and FreeBSD work just fine with UEFI but not with SecureBoot.
Although Microsoft told OEMs they may (wink, wink, nudge, nudge!) allow users to disable SecureBoot, this is not always the case. At best they will allow you to disable UEFI altogether which means you can't dual boot. You'll be able to boot into one ore another by going into BIOS to toggle UEFI. Clever Microsoft, they just made it inconvenient enough to discourage large masses of users to explore other OS.