ain't your buddy, pal!

I use "fam".

they are kinda a gender neutral.

Bro is fairly commonly used as gender neutral word.

Man (as in my man) does not have an equivalent (my person does not havve the ring) - but originally, man was the gender neutral term for persons, and we user mer (as in mermaid) / were (as in werewolf) for males. that is how man was used. But that very well could also be due to bias in writing and archiving of stuff, I don not know much about this.

I'm old, but my even older inlaws refer to each other affectionately as "person."

People say "dude" is neutral, but you don't often see it used when all the dudes are women, and the existence of "dudette" also implies it's not.

"Friend" maybe but could sound sarcastic.

Come to think of it, all these terms are ripe for sarcastic use. In fact, I'd like to see the map of antibrotymology. Which of the above is used the way Wolverine uses "Bub"?

Cuz is acceptable

Sib (as in sibling) is my preferred one.