There is a good chance it could be proved because Bragg actually campaigned on indicting President Trump. It was one of his main campaign points and from what I have read is totally illegal, but Democrats never get in trouble for doing truly illegal things.
I suggest someone put together all Braggs statements, video newspaper etc saying he was going after trump and make a political ad about it..and give it to the NY bar as a complaint
I think all 50 state Bars are populated by leftists and thus all are corrupt to the core. There is a better chance of Hell really freezing over than a state Bar yanking his law license.