I have 3 yorkies, Lexie goes on washable pads, she will go outside too. If it is raining she prefers to go on the pad. Zander knows what the pad is for but prefers to hold it and go outside. Jazzie would rather explode rather than use a pad

but she knows what its for too, go figure.
I have seen a place that sells the grass and tray with a fence to go around it, very cute, I have also seen a fire hydrant for boys that goes on the grass.
Good luck