Linseed oil has only been in vogue since hemp has came under criminal scrutiny in last 80-90 years. Linseed oil is cheap, it is a good second choice. But hemp oil HAS been used for centuries in fine oil paints.
From the 'Net...
Hemp oil is a "drying oil", as it can polymerize into a solid form. Due to its polymer-forming properties, hemp oil is used on its own or blended with other oils, resins, and solvents as an impregnator and varnish in wood finishing, as a pigment binder in oil paints, as a plasticizer and hardener in putty. It has uses similar to
linseed oil and characteristics similar to
tung oil.
Rembrandt and Van Gogh both painted on hemp canvas, using oil paints made from hemp oil.
Seems to me hemp oil would be an excellent choice all around.