I suggested those solutions because normally they work in some cases, but I didn´t try the game myself because I don´t have currently a suscription to Teknoparrot.
I don´t even know if the game works or not on my own PC.
What elf file are you using ? You should use the one called "chopperM_HD.elf" if you want to play the game in high resolution. I have read that using the HD elf, the game goes fullscreen.
If any part of the graphics like the coin, is misaligned, then you should hex edit the elf. Please ask on Discord about it, surely someone will help you to fix it.
You can also try to upscale the game using Magpie, it´s worth a try to see the results. If you want to use Magpie you have to previously set the game windowed, and then upscale.
In order to use Magpie , you should modify Nvidia panel "Adjust Desktop Size and Position" section and set to "Aspect ratio" or "No scaling" ( not sure which one ), and also untick "Override the scaling mode set by games and programs", because otherwise it would mess with the upscaling done by Magpie.