Here is the most scientific version of this I could find from that article. I’ve got work to do, but I’ll try to come back later to add something else.
There shouldn’t be any barriers to entry for this. It won’t be as cheap, but NIRS is not prohibitively expensive.
This is just really new. It takes lots of time for completely novel medical devices to enter the clinic.
This is also vastly more advanced than a pulse ox.