I agree with your assessment of how masculine stereotypes discourage men from showing affection. Before I transitioned voice was one of the first things I started to notice I didn’t like. I’m a teacher and wanted to indicate that I care for students but because of my masc military voice I still sounded forceful and intimidating.

A good example of a masculine man using low resonance to show vulnerability is Rorschach in the final scene where he begs Manhattan to kill him. He sounds smaller and out of breath since he is on the verge of tears. Manhattan pities him because of his desperate and submissive position. Only when he reverts to his resonant large voice does Manhattan grant his wish and kill him.

Tapping into fem coded emotions in the voice could give a pathway for cross sex voice training for mtf. E.g. “okay try it like you’ve met a puppy. Try it like you’re begging. Try it like you’ve been shrunk.” All fem coded situations: caring for a baby; submitting to authority; being physically smaller and weaker.