Converting a big HTML source page into mutliple MD posts


I am using a GitLab theme for this:

and you can see for the PHR section I have added an accordion for the posts (thanks to people here for that help!) - which I like - but I would like to be able to create posts in _posts/phr/ or _include/phr/ in MD rather than one big HTML flke in the current _include/ - that would then get included into the accordion - is this possible to do somehow? is it a sensible thing to do?