In terms of usage, it is not a restriction as long as your requirement
for your site page is met with XF page rendering component
itself.(Inspect the html files as part of your xf page rendering
component, if it meets the definition of your site page - use the same.
Otherwise, per adobe recommendation, it is to make use of Core Page
component for site pages.)To answer how to do that - it is same as any
editable template creation steps - create editable template-type (with
desired page rendering ...