Baeically its a somewhat stripped down version of plasma ment to be used with a controller or remote, but it is only a DE, so applications that arent controller friendly are going to stay that way.

Setting steam to launch big picture by default tho would basically turn any powerful pc you have into a steam console (steam big picture) with an extra home screen (plasma bigscreen) that shows all your other applications

This should be a well know, but often misunderstood thing. Lots of reddit selfhosting threds urge people to buy a new mini-pc for its “low power draw” when usually its the same or 1-2watts less then a laptop from 2012. However performace to watt is much higher, so if you need massive preformance new is much better, if your system is idling most of the time anyway, basically no diffrence in buying old