I've never taken "Unsound Openers" absolutely literally - I think of this group as being dedicated to offbeat and risky openings including a lot of gambits, where many, but not all, of them are unsound. My opening repertoire has been this way for about 17 years and when I mentioned my long-standing membership of the group at local chess clubs there was a strong consensus that belonging to an "Unsound Openers" group sounded highly appropriate for me...
Has anyone given that Caro-Kann Bayonet variation a try? I'd be interested to see some games from others and their take on the lines. https://www.chess.com/clubs/forum/view/caro-kann-defense-advance-bayonet-attack-with-e6
Generally, it is to give them a material advantage or some other concession for compensation in the form of accelerated development and/or open lines/pressure. The idea is you have to make use of that compensation quickly, else more likely than not find yourself in a worse game. Objectively, the opponent can usually thwart the attempt with perfect play - but familiarity should work in your favor and their defense may be complicated or challenging over the board as well working in your favor.
Is the whole idea of an unsound opening to give your opponent an advantage at the start of a game and then out play them in middle and endgame. I am quite familiar with this from checkers. Give up a checker or two because most people are terrible at checkers then outplay them. Only way you can get a challenging game.
I created a TUO tournament. Do all join to become the Unsound Champion! If registration isn't full after a week or so, I'll share the invitation link with some other gambit groups. ;-)
https://www.chess.com/tournament/the-unsound-openers-championship
I am defending against a sodium attack in one of my daily games at the moment. My opponent has just blundered their Queen. BEMPI0, would you like to play a friendly game with an Unsound opening?