Some of the hidden gems I've come across:
Escape the Obelisk
https://itch.io/jam/gdevelop-big-game-jam-9/rate/4607221
Ascendisc
https://itch.io/jam/gdevelop-big-game-jam-9/rate/4607572
Barto's up!
https://itch.io/jam/gdevelop-big-game-jam-9/rate/4607552
Little Space Boy 2
https://itch.io/jam/gdevelop-big-game-jam-9/rate/4604631
Mystery of Earth
https://itch.io/jam/gdevelop-big-game-jam-9/rate/4587605
And here's my game, The Final Tower
https://itch.io/jam/gdevelop-big-game-jam-9/rate/4608259