An iPad, backing tracks and mixer costs significantly less and is much easier to carry and setup up for solo players/singers, (Go and watch some live singer etc. and you will find it has been the standard for donkey's years) so unless you have one lying around and are prepared to create your own backings, then it of no use.
Ass to the light system then that was done donkeys years ago when automatics started to be added to organs in the 70s.
The last one is interesting until you realise that you can get mixers with them built in, or even do it on the iPad.

Bill