I think it would be useful to offer a project page template (a skeleton, not a MediaWiki template). Project owners could adapt it, deviate from it or ignore it completely, but having a common reference would be useful.
For instance, in the context of the Onboarding New Developers program, we want to define criteria for Featured Projects. One of the criteria is a decent project page. However, what makes a project page decent?
CC @AKlapper (WMF)