Here’s a possible real risk when it comes to systemic absorption.
Rogaine has been most known as an antihypertensive drug, long before any more recent anti-androgen properties were discovered.
Hair loss drug recalled for ingredient that can put users ‘at risk for heart failure’
https://www.miamiherald.com/news/health-care/article242664821.html
Topically, Rogaine should have a very low systemic absorption rate, the same would go for any anti-androgen effects, it should be localized.
I would first be thinking loss of skin barrier function or increased skin permeability, if at increased risk for side effects.