alt bros are guys what are usually lads, that latch on to the idea of being alternative. usually by wearing stuff that is 'in' like the snapback hats. swag bros are the same except they appropriate elements of hip hop culture. alt and swag bros probably use the word "banter" and aren't really interested in music
And here I thought you meant 'alt' country. Like John Deer trucker hats and check shirts.
I think I only know divorced dad bros.