Using straps as a sort of faux safety-squat bar is great for lunges, split squats, and Bulgarian squats. Why? Because it reinforces the hip hinge. You can easily make a safety squat bar using a set of straps. Simply take two lifting straps/wrist straps, loop them onto the barbell, and space them an equal distance from the center knurling.

You have to keep your hips set back almost maximally throughout to create a slight forward torso lean. In other words, it promotes ideal lunging and split squat mechanics.

It also forces you to stay in the bottom three-fourths of the movement because locking out or coming up too high at the top of the lunge will cause the torso to become overly upright, resulting in bar slippage. The amount of constant tension is incredibly high, making it very effective for spurring gains in functional strength and hypertrophy.

Just be prepared for a serious burn.