Did you know that there is a widget for KDE Plasma with which one can read comics and co on the desktop (or in a panel)?
I didn't know until I stumbled over the comics page in the KDE store.

After tinkering a bit with such plugins, I created a Repo with some plugins.
This also contains a plugin-template with which you can easily (if I got it bug-free) create a plugin to read manga from MangaDex.

I wanted to let you know in case someone is interested to try it.
Feedback is always welcome.