I got some random generic one. I wouldn't recommend it as the quality could've been better. For you, I also tried tape over the mouth. I got a wide washi tape from a friend and experienced similarly helpful results to the chin-strap. However, I found that comfort-wise, I preferred the chinstrap.

But, if you can breath through your nose well enough, I think some kind of mouth tape can work? I haven't tried the Hostage brand anti-snore tape, but maybe someone here has had experience with that.

If you really want the chinstrap that I got, I got this one: https://www.amazon.com/gp/product/B08DR16XGV/

Based on the pictures, it obviously pushes the jaw backwards. That obviously wouldn't work for you. I wear mine in such a way that it is helping my jaw close and stay shut. I agree that you don't want something pulling your lower jaw backwards.