Could you frame a conversation with them as seeking advice about someone other than yourself? “One of my classmates is coming out and I want to support them, what do you recommend?”

Their reaction and advice could paint a pretty good picture without putting yourself in their crosshairs. Worst case, you can refuse to name the person and maybe get grounded for protecting someone imaginary.

But yea, that won’t give you a complete answer to how they would react if their own child came out.