We would appreciate very much that SonarCloud were integrated with GitHub Enterprise on cloud in order to allow the PR decoration and for applying Quality Gate rules on PR to master
SonarCloud is made for fully cloud-based workflows and thus SonarQube is a better fit when used with on-premises setups such as GitHub Enterprise. You can find more information and guidance around this topic in this blog post.
GitHub Enterprise may be hosted locally, it is still a cloud service, right? I don’t see any difference between supporting github.com and e.g. github.mycompany.com for SonarCloud.
Azure DevOps support both GitHub and GitHub Enterprise for their pipelines. the only difference is that in the latter case you need to specify the URL yourself. Why wouldn’t this work for SonarCloud?
We work with GitHub Enterprise as if it were a Saas service and as @tzijnge has stated other solutions give support to it. If we couldn’t find a solutions on applying PR restrictions from SonarCloud analysis we will be forced to leave SonarCloud