In what case did you need that package?

This package gives utilities to query neon a vfpv3 cpu support.

This is on Ubuntu 23 64bit from the official Raspberry Pi 5 imager.
I enabled Dynarec and using the Pi4 profile otherwise.
Without this package the make -j4 step fails.

After installing it and rerunning cmake the compilation works.
With this I managed to start steam and tested game streaming from a Windows PC to the Pi 5.

What is strange about this is that I compiled box64 first (in hopes that wow64 would just work and I can get away without box86), which has a Pi5 profile and for some reason it didn't fail compiling.

https://packages.ubuntu.com/mantic/neon-support

Maybe it's functionality is redundant with some other package that machine also didn't have.

That said the whole setup is just very slow, doesn't feel like what's seen on this video: https://www.youtube.com/watch?v=co3Qi9ZwS5Q

The video you linked was recoreded on a arm machine that have real AMD Rx550 graphic card (well, a laptop model, so 64bts bus, but still a dedicated graphic card). I don't think the PI5 GPU is as fast as this graphic card.