Malgus mentioned the acacia bush. I’m not familiar with that plant but I can suggest the rugusa rose for fence lines or under windows. They are impenetrable and will shred your skin if you try. As an added bonus you can make tea with the rose hips, they are very fragrant and rather attractive when in bloom. Perhaps the best part is they will grow just about anywhere. I had some at my last house and would cut them to the ground every few years when they started getting a little ratty looking and they’d quickly regenerate into lush new bushes in a single season. They’ll even grow in sand at the beach. Up on the Gaspe Peninsula of Quebec, a truly wild frigid terrain where mountains abruptly descend into the ocean, the only shrub you’ll find around homes are rugosa roses because it apparently is the only shrub that survives the climate. They will also get as big as you’ll let them via sending off runners that new shoots come up from.