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...
The magnetic board has a metal strip on the right and left, in which the holes for the screws are located. Theoretically, you could also apply double-sided adhesive tape or strong glue to the strips and stick the board to the wall that way. However, I don't know how well that would hold.
Of course, it depends on what you want to attach. Strong magnets would be appropriate for multi-page or thicker items, but "normal" magnets are certainly sufficient for 1-2 page items.