When controlling a load with a triac coupler, can a load be controlled even if using a rectangular wave power supply at the load side instead of a sinusoidal wave (AC) power supply?

When controlling the turning ON/OFF of a load with a triac coupler, the power supply is intended to be used at a commercial frequency of sinusoidal wave.(50/60Hz). Using a rectangular wave power supply is not recommended, because if doing so, high-frequency components contained in a rectangular wave may cause malfunction.