Waydroid works ONLY in a Wayland and you need to run a kernel which
comes with the binder modules.  Slackware stock kernels dont come with
that.  There are several ways to fix this. What I preffer is the hard
way, to build a Slackware zen kernel.  Using stock slackware kernel
config plus: CONFIG_ANDROID=y CONFIG_ANDROID_BINDER_IPC=y
CONFIG_ANDROID_BINDERFS=n
CONFIG_ANDROID_BINDER_DEVICES="binder,hwbinder,vndbinder"

One of the reasons is that I found it the most stable and secure way...
NOTE zen kernels its BETTER to build them in $USER/HOME not to root and
better not to /usr/src so make as user $HOME/ZEN and build there.
============

Next step install python3-gbinder from SBo/ponce

I use slpkg for that.  # slpkg -i python3-gbinder (this command will
build and install python3-gbinder deps too) ============

Then run ./waydroid.Slackbuild to build and install package.
============

After installation finish run

# waydroid init or init with GApps support # waydroid init -s GAPPS

^^ this will automatically download the latest Android image.
============

To start waydroid session: # /usr/bin/waydroid -w container start &
(give it some time...)  ===========

Launch GUI:

$ waydroid show-full-ui

Launch shell:

# waydroid shell (bug)

Install an application:

$ waydroid app install $path_to_apk

Run an application:

$ waydroid app launch $package_name # Can be retrieved with `waydroid
app list` ===========

TIP: If you affected by: "ContainerManager:
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NoReply:
Message recipient disconnected from message bus without replying"
 
 Try: # pkill -HUP dbus-daemon

and command again...  ============

TIP: If you get error `Failed to get service waydroidplatform, trying
again...`

Try: `waydroid upgrade -o`

============

good luck, you gonna need it! :D