Okular can view CHM files, to do so it uses KHTML, makes sense CHM is basically HTML with images all compressed into a single file.
This is somewhat problematic since KHTML is largely unmaintained and i doubt it'll get a Qt6 port.
The problem is that the only other Qt based HTML rendering engine is QtWebEngine and while great it doesn't support stuff we would need to use it in Okular, since Okular needs to access to the rendered image of the page and also to the text since it uses the same API for all formats, be it CHM, PDF, epub, wathever.
The easiest plan to move forward is probably drop CHM from Okular, but that means no more chm viewing in KDE software, which would be a bit sad.
So I thought, ok maybe I can do a quick CHM viewer just based in QtWebEngine without trying to fit it into the Okular backend to support different formats.
And ChmK was born https://invent.kde.org/aacid/chmk.
It's still very simple, but the basics work, if you give it a file in the command line, it'll open it and you'll be able to browse it.
As you can see it doesn't have *any* UI yet, so Merge Requests more than welcome.