Can a men dip in the mikva wearing a rubber band or a pin on his beard?
Is it considered a chatzitza?
If yes, is there a need to unroll ur beard before toiveling?
Halachically you don’t have to remove the rubber band or pins before to go to the mikvah. The reason for this is that for tevilas ezra, we are not makpid that there should not be any chatzitzas. However it is preferable that you enter the mikvah the same way that you would take a shower, and take them off. the same way you would take a watch off (if it is tight against your arm) before toveling. You don’t need to unroll your beard before toveling, as a man doesn’t have to separate hairs etc. before entering the mikvah.
Be’er Moshe 5-20, Pischei Teshuvos 68-8.