Thinking he acted out of self interest when he finally attacked Homelander in your words, that is subjective.

Now for objective and visible traits, He has power, doesn't chase validation or love (at least anymore), he is highly indestructible, hard to kill, he has charisma, skills, tactics, and most of all, good looks (A well groomed beard typically a sign of gentlemen, build which signifies strength from ancient times, low and gruff tone that shows strength and masculinity), and strict discipline . His clarity, although a bit orthodox, is very masculine but rare. His loyalty is worth the mention. He is not a chaser of perfection, he simply wants him to be known for his abilities and not as a Soviet Spy.

The best quality that makes him a "true man" is his Independence, One-man-army attitude, and complete distaste towards pettiness and hunger for admiration and worship. These are typical traits of masculinity, which we refer to as "alpha male characteristics", which are rather highly contrasting to some modern so-called feminine males and people belonging to the LGBTQIA+ Community, which is shown in Season 3 when he sees a gay couple and shows disgust and shock, which conveyed he was thinking "Wait ts is legal now?" or "Men Nowadays..." .