I was having the exact same problem, but libudev is not there anymore. I found out that it got merged into systemd now (see this post: [SOLVED] `libudev` replaced by `udev`? - #3 by jonringer)
I use a package that is based on Qt6, but it uses the Qt WebEngineCore.
It’s the same fundamental problem as it’s based on the Chromium browser.
I just added a
patchelf --add-needed libudev.so.1 $out/lib/libQt6WebEngineCore.so.6
and now it works.