Looks cool, and overall everything is clean and styled. We can put third party headings on any contributed files, like the decoders, with a smaller Marlin "This file is part of..." heading instead of the whole GPL precursor. In general, such a lesser header could be placed on all minimally-modified library files to emphasize their own (often more open) licenses.

The image reminds me that we need to fix up that "remaining time" estimate. It's been bugging me. The remaining time estimate starts early in the print before calibration and heating, but it should wait for the first printing move and subtract all the previous time and the SD Position for the rest of the estimate. This will make the estimation that uses the file position a little bit closer to true, and get rid of the useless estimation before the print gets started. Other heuristic adjustments can be made, but of course letting the slicer provide the remaining time estimate will always be best.