No browsers support those features from all the testing I've been doing over the past month or two. Weasyprint supports everything I tried except target-counters and dot leaders which I've only found support for with princexml. Weasyprint does author a proper outline within the PDF so my current workflow (no $ for prince) is to use Weasyprint to make the PDF with a TOC that has no page numbers, extract the outline from the PDF with a python tool to get the page numbers, update the original HTML with page numbers then run it through Weasyprint again. That'll be bundled in an automated build thing triggered by a git commit of the original markdown file straight to PDF so it's not something I have to do manually each time.