Hyperpixel 4 - Pi Zero 2 - Video Looper

I am working on a Raspberry Pi Zero 2, battery operated video looper using the hyper pixel 4 display. It’s working great and loads videos from a usb no issues there.
Only problem is the 480x800 .mp4 files are squashed. I have tried lots of different resolutions - strangely the more square format is, (1280x1280) the less the mp4 is squashed.

I have tried making changes to the config.txt file such as:

framebuffer_width=480 (1280)
framebuffer_height=800 (720)

which unfortunately didn’t work. Anyone here encountered this problem before or have an idea of how to make the videos fill the screen properly? Any help would be much appreciated, It’s my first Raspberry Pi project and it would be great to get this working so I can move onto printing the case.

many thanks.