On Linux most PDF viewers are poppler based, we have also mupdf but its interface can be a bit too simple for some users. When some PDF is not properly rendered by poppler, people can be a bit upset after seeing it was ok from firefox or Chrome but, once downloaded, don't. chrome and chromium can open PDF files simply running "google-chrome/chromium ...pdf", I would then append pdf to the list of MimeTypes for the desktop file to be also offered as an option when people try to open pdf files. Thanks
Please propose your change upstream. https://crbug.com/ This file would need to be modified. https://chromium.googlesource.com/chromium/src/+/refs/heads/master/chrome/installer/linux/common/desktop.template
they fixed it in upstream :O https://bugs.chromium.org/p/chromium/issues/detail?id=1046912
Oops, correct link: https://chromium.googlesource.com/chromium/src/+/647f8ae0c1121822643c73af87986d9591e669a4
Nice! I guess we will pick this up in a dev channel release soon.