Are you open to contributions? I would love if there was a non-chromium alternative to wkhtmltopdf!

wkhtmltopdf is not chromium though? "Wk" literally stands for WebKit.

There's also https://weasyprint.org/ which doesn't use any browser engine, but rather a custom renderer.

And both of those (and Prince) can be used as a backend by Pandoc (https://pandoc.org/)

like https://www.princexml.com/ ?

Yea, Prince is awesome. Not FOSS tho. I make some GPL or MIT licensed software and wish there was something as good a Prince with more open license.