Thanks a lot.
I copied the dt-blob.bin from the LibreElec into boot-folder and the slice.dtbo into the overlays-folder.
With that I could use the keyboard and a Wifi-Stick.
At the first start the OS wants to update and after that update the Slice won't start anymore (or at least the HDMI and Wifi is not working anymore). So for the next start I didn't do the update and I could work.
I will try to figure out if there is a way what I can do to update the OS.