I doubt SAGD is applicable here. Oil sand is sand coated with...

I doubt SAGD is applicable here. Oil sand is sand coated with bitumen. Heating the formation with steam gets the bitumen to flow. Oil shale contains kerogen. Kerogen is a solid that has to be heated to much higher temperature (>350C) to cause a chemical reaction that decomposes the kerogen to oil. Also the shale is relatively impermiable compared to sand.
Thats not to say that insitu extraction of oil from oil shale is impossible. There are a couple of companies in USA and Israel looking at insitu heating of oil shale.