Signing e-mails and PDFs with Belgian EID on Linux

With the current Covid-19 lockdown, more and more transactions are getting handled remote. In Belgium we have the possibility to legally sign documents with a certificate stored on our eID (smartcard). However... when I started looking for information on how to do that on Linux, I could only find partial info. Mainly on how to use LibreOffice to sign a document, but not on how to use your Belgian eID there. Or information on how to sign a PDF with eID on Windows or Mac with Adobe reader, but not on Linux.