I’m not aware of one, but there are instructions for building and packaging custom firmware for the 2.0. From what I hear, Snapmaker doesn’t pay much attention to github pull requests though.
On my Original, the progress bar is a percentage of the file, by bytes. I can get a rough idea of the layer by finding the layer in the GCode, then dividing by the file size. It’s not perfect, and the display is only whole percentages :-/ Still, it’s usually enough for prints with less than 100 layers.
As a workaround, I just calculate the layer based on the layer height and Z height of the nozzle as reported by Luban. That works fine for equal thickness layers, but I typically use Simplify3D v5 as a slicer and use the adaptive layer height feature where the layer height varies depending on the contour of the object. The calculation method is much more difficult in that case and there’s no way to easily determine the layer number other than a comment for each layer.