The reason that I ask for these features is exactly that – converting existing Posts into Pages is hacky and awkward.
Could not agree more. I came from WordPress/Ghost, and found Publii easy to use. But creating a page was a very tough job for me, initially. I had to go through developer docs and do some coding stuffs to achieve the desired output.
I can create a post template and make it like a page, but the whole point of using publii is to make the lives of non-devs easier.