Waydroid in this tutorial is running in a “cage” so it can run under X11 which is an older system used by the current KDE version in the steamdeck.

To install it on bazzite (under Wayland instead of X11), it’s even simpler.

   rpm-ostree install waydroid

and

   sudo dnf install waydroid

So if you are ussing bazzite, follow first option here