The Raspberry Pi Display that I have is also the official 7" touchscreen display. I also have found that if both a HDMI display is connected along with the 7" touchscreen display, it does get past the Kodi splash screen. Because of this, with the current release build, I've had to connect a HDMI display so that Kodi would come up all the way on the touchscreen display, and it does get annoying having to do this after a while.
I'll try a nightly build from test.libreelec.tv and see what happens with that one. Thanks for the info.