Scale factors

[oyhj1801]

Hi!
How would I go about converting grid distances to real distances?
Is there a way to caluculate the grid scale factor given a position and crs?
I saw that both the projdata and the k0 in the projdata is pub(crate) so not accesible from the outside.
But I don't understand how the k0 relates to the actual scale factor as I thought that was a function of position as well

And is there a way to calculate an elevation scale factor based on the same + height above sea level?

Thanks for the great crate!