wyldcrd

Fails to mirror? As in black screen or a game crash?

The vivecraft mod tries to get vivecraft and vanilla movement 1:1 I believe. Reason? Because anticheat on servers and moving faster is unfair. However a singleplayer movement multiplier slider is...

A separate mod that has a speed slider probably exists though.

All an fov slider would do is stretch the screen, not give you an actually wider fov.