Things are so hard right now in the pandemic and this has given me a little virtual hug.
Big thanks to the eng team at https://charm.sh/ who wrote the terminal library I am using and showed up with prs and great ideas.
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.