Hi @yatil 
When I migrated my blog from WP to Kirby two years ago, I wrote myself a custom-tailored import script (it looked like straight from Frankenstein’s laboratory; dealing with a decade of all kind of custom fields, shortcodes, extensions, comments, webmentions etc.etc.) where I rendered the Wordpress-HTML (exported as a WPXML file) to Markdown using GitHub - Elephant418/Markdownify: The HTML to Markdown converter for PHP as I created the Kirby pages.
This worked reasonably well, but required quite some adaptations to both the input and the output (mostly automated with regexes, but also some manual touches) to get it right. In hindsight, it probably wasn’t worth the effort, but I do have all my old content in clean(ish) Markdown, which I consider best for long-term archiving. And it’s of course cleaner markup in the rendered pages.
…that said, I still encounter errors in old posts occasionally, so perfect this wasn’t 