I'd say the weight is at least 1Kg and it gets heavier the more magnets and stuff you put on it. And the backside is not flat. If you look at the last picture below you'll see there's only a small border, too small even for strong stickers. So a solution without screws must be more sophisticated....If you stick a flat shelf with a gap on the top to the wall and then slide this board into that gap. (from my point of view)
https://www.zeller-shop.de/main...