HLSL doesn’t have byte types. You can pack the bytes if you want, but it’ll be more expensive. It doesn’t matter for sending the data, because the conversion to bytes happens on the GPU.
I’ve used bytes for position before in a voxel engine that had chunks of 256x256x256 (or smaller) voxels. By setting uniforms with the starting position of the chunk and the voxel size you can make do with bytes.