Have you thought about some prickly Cactus???
Cactus here is a lot like lilies and cannas. Guam is pretty strict on importing non native plants and I don’t think I could buy the plants. At least I haven’t seen them available. There is a six to seven foot tall decorative stone fence across the front of he property and crime is actually pretty low here so I am not doing this for security but stop a nuisance and to beautify the street and add curb appeal to the house.