A CPET is a cardiopulmonary exercise test. The 2 day CPET is when you get the test and then get it again 24 hours later.
People with me/cfs have different results than sedentary controls, so it's a good way of helping prove disability.
If you didn't know what ME/CFS is (myalgic encephalomyelitis) then you haven't been diagnosed with it and none of this applies to you, but I thought it was worth mentioning in case you had.
That sucks in terms of proving disability in your country (you would be eligible already in mine but since disability here is only half of minimum wage it's not really the solution like it is where you are).
But it's really fantastic that you are able to do so much!! That's way better. You're going to be able to work from home lying down. Lots of cool ideas in here.
I think you should still apply for disability every year. Maybe find a support group or organisation for people with broken necks/spinal injuries, they might know some aspects of the process.
Good luck to you. I know what it's like to lose everything, and I really hope you are able to rebuild some kind of life for yourself.