From looking at the github, I think you don’t need to/want to host this publicly. It doesn’t automatically get and store your information. It’s more a tool for visualizing and cross referencing your takeout/exported data from a variety of tech platforms. It’s just developed as a web app for ease of UI/cross platform/ locally hostable.
I’ve setup okular signing and it worked, but I believe it was with a mime certificate tied to my email (and not pgp keys). If you want I can try to figure out exactly what I did to make it work.
Briefly off the top of my head, I believe it was
I can’t remember if there was a way to do this with pgp certificates easily