Can I use a newer version of Ubuntu on hardware that is only certified with an older version

The version of Ubuntu shown when viewing the details of a Certification indicate the Ubuntu release the hardware was certified with. This means that the hardware is considered Certified and officially supported for the life of the release used for Certification.

In short, if a system is certified with 18.04 GA, it will be officially supported and certified until the 18.04 LTS family is EOL in April of 2023 and is then covered until the Extended Security Maintenance (ESM) period expires in April 2028.

This does NOT imply that any NEWER versions of Ubuntu will not work. Quite the contrary, newer versions of Ubuntu should work well.

What this does mean is that a system may not be considered Certified for that newer release. For example, using the hypothetical system mentioned above, which was only certified for the 18.04 LTS series, that system should be able to run the 20.04 LTS series, but is not Certified for the 20.04 LTS series.

This means that there may not be official support for bug fixes and technical support if issues are encountered and it will be up to you to seek out support through Ubuntu Advantage (https://ubuntu.com/advantage) or by community means (https://ubuntu.com/support/community-support)