[rbanffy]

That's really cool!

If you want to further add vertical resolution, Unicode 13 introduces 2x3 mosaics (from the TRS-80, Teletext and others) that are supported directly within VTE (so people don't need to install a font). Slightly more complicated are the "smoothed" mosaics (from Minitel 2, IIRC) but they offer diagonal lines (and complement PETSCII and ATASCII symbols also introduced in version 13).

I expect 2x4's to be available for version 14, but it'll be a while.

2x3's (and 2x4's) are kind of funny, because you still won't be able to use more than 2 colors per cell, so it works for cells with two colors but that can be subdivided in thirds (or quarters). Finding a best fit for a cell and a mosaic is not a trivial job.