Google has release Chrome 0S 121 which makes it easier to install debian 12 on a chromebook. (Note: not all chromebooks are created equal so this may or may not work on yours.)
ChromeOS 121 brings a big Linux upgrade to Chromebooks
ChromeOS 121 will bring the Linux upgrade from Debian 11 to 12 on Chromebooks. I tested it out and it worked perfectly. Here are the details.www.aboutchromebooks.com