This isn't a thing. You'll need to provide more information than you have. While Dell does sell "certified" hardware, they have never (AFAIK) locked down a sys

This isn't a thing. You'll need to provide more information than you have. While Dell does sell "certified" hardware, they have never (AFAIK) locked down a system to only allow Ubuntu installs. I don't even see how this is possible, provided Canonical doesn't supply Dell with Secure Boot keys locked in the BIOS/UEFI -- what you're describing has never been a thing, and was most likely an issue with storage controller or lacking support for a chipset generation.