How would you treat a patient with oligometastatic disease to the lung for whom SBRT/SABR is not feasible?

I am not sure what this means exactly, as far as not technically feasible. Very old machine? Lack of dosi/physics support? If you can do VMAT with image guidance at your machine, you can probably do SBRT/SRS. You just need to have physics do their thing.

In America, we use a billing definition to c...

If it is not technically possible because your machine does not have the feasibility to do SBRT (say, a machine that only does step and shoot with kVs, without VMAT or CBCT), then I would refer the patient out to a center/machine capable of doing SBRT.

If insurance does not approve it, despite p2ps ...