I’ve tried it. My youngest (21 months) can definitely inform us that she needs to go to the bathroom. But she’s not quite ready to use the toilet. She either doesn’t want to sit on it, sit long enough, or gets distracted. The kid definitely needs to be open for potty training in order to it to work.
My oldest was potty trained at exactly 2 years. We just let her run around without a diaper and there was one specific time she peed that everything clicked for her.