There are many already available, e.g. ZedBoard, someone just has to do the work to target these other boards and their peripherals/layout.
I am keen on the MiSTex project though. The plan is to come up with something that is more flexible than MiSTer to support different targets. So for example, you might be able to target a simpler core to a simpler device and vice versa.
… OP didn’t mention they were optimizing for price.
Some might say it makes sense to optimize for availability, recent updates to hardware software stack, etc.