Are there any legal drugs that do what marijuana does in palliative care?

Yes.. There is a fairly old drug we have used for nausea and to stimulate the appetite in patients called Marinol (dronabinol). It is a cannabanoid (same thing in mj). Comes in tablets; taken a few times daily based on the reason for taking. It fairly expensive and a controlled substance. Schedule iii. For people on chemo w/ lots of n/v it can b wonderful.
To a degree. Dronabinol (marinol) is a synthetic thc that is taken orally and has been shown to have both anti-nausea and appetite stimulating effects for many patients.