I used the WP Import feature when I switched from WP to Publii for my personal blog. It worked fine: https://www.callmefred.com/.

All details in this post: https://www.callmefred.com/i-switched-from-wordpress-to-a-st...

Not very reliable. There are many reports of problems in the public forum: https://forum.getpublii.com

Seems to be working well for my small blog. Only issue is pages don’t import well, I would export only your blog posts.

It works. But it only works for standard WP stuff. Throw in a non-standard gallery or something, and it will degrade.