Wherever you are located (secret), ask a contractor or architect. Electric heating material for floors is a standard product. When we redid the master bath the floor changed to marble (long-time wifey wish) with electric heating underneath and a thermostat on the wall, all off-the-shelf standard stuff.
Pet pig in the garage? No, I think he is growing some Mary Wanna and the bright lights should keep it warm enough. Do plants need to sleep with the lights turned off? Then they might get too cold.