Install KDE inside VMs

Hello Qubes Community.

I have actually install KDE as a desktop environment with this guide : KDE (desktop environment) | Qubes OS.
However, inside my VMs, it is still XFCE and it doesn’t integrate well with KDE. For example, if I use a KDE app like Merkuro Calendar (new name for Kalendar), it will lack some icons, typo, graphical feature, etc.
How could I set up KDE inside my VM to make a uniform look and feel and a coherent and complete user experience ?