I was postponing but now I did the update. After testing basic stuff with the usb stick (wifi, audio, video, etc), I had to figure how to install focal-somerville-ygritte packages. You can reproduce this on usb stick before installing. First you have to backup /etc/apt/trusted.gpg.d/ to copy later on the new installed system. I needed only the files that match *oem*.gpg. Also backup /etc/apt/sources.list.d/ with files focal-oem.list and oem-somerville-ygritte-meta.list. After installing the new version, put the mentioned files in respective folders. There is a dependency on one focal-security package, so edit /etc/apt/sources.list and copy all lines with jammy-security, changing them to focal-security. Then execute:  
I want to do a fresh install of ubuntu 22.04 (especifically xubuntu) and after installation add the source lists I have in 20.04 for dell packages. My hardware (Optiplex 3090 Micro) is targeted with version focal-somerville-ygritte. My questions are: There will be a jammy-somerville-ygritte? The existent jammy-somerville is compatible with my hardware? Or I don't have to upgrade the external sources' version, just add the 20.04's sources lists as they are now (referencing focal)? AFAIK those packages are just for energy optimization, maybe an alternative its don't have them installed.
Ubuntu fresh install (22.04) with Dell's external sources