You can 100 percent donate bras that are in good shape! In my area in the midwest there's a ton of big brothers big sisters donation bins for clothes that go to teens, I like donating good quality clothes to those. People also mentioned charities for trans people to exchange clothes, those shouldn't be too hard to find if there are any in your area. My area also has a homeless shelter with a section specifically for women escaping abusive situations that i like to donate things like that to. Goodwill will definitely accept the bras if they're in good shape so don't throw those out, they're an item that's in high demand.