Using a HexEditor (I used HxD) open:

steamapps\common\New Super Luckys Tale\nslt_Data\Managed\Assembly-CSharp.dll

search for all Hex instances of

39 8E E3 3F

and replace with

3440x1440 - 8E E3 18 40
2560x1080 - 26 B4 17 40

Other resolution HEXs can be found by Googling.

(Should be 7)

Doesn't fix zoomed menu, but no more bars.