SUMMARY
The new feature for digitally signing PDFs is great! As a Linux user, this was the last thing that kept me from needing a VirtualBox with Windows installed. Just for signing PDFs, so thanks so much for the implementation.
As a potential future step, I wanted to suggest the following feature.

It would be useful if there would be a way to digitally fill out PDF forms and digitally sign them directly on the web browser, within an embedded plugin for okular. So to say, that when I develop my web server using PHP (or HTML), I have the option to add a PHP or JS snippet, to offer the users filling out a PDF form and uploading their certificate using an embedded version of okular (that runs on the web server, behind the scenes). This way, any user could fill out and sign forms from the phone, etc. without needing to have anything special installed.

Thanks in advance!