Taiwan's Lost 8-Bit Computer [video]

The way the hardware is set up, you wouldn't be able to display anything onscreen that's not one of the predefined font characters, so it's not that much of a loss. The official Nintendo BASIC cartridge had the same issue, but at least on that they had a bunch of tiles that could be used for games rather than just font characters.

If you're interested in this sort of thing, the most advanced keyboard famiclones were made in the mid-90s by BBK Electronics. They had a floppy drive, BASIC interpreter, assembler, and debugger, and ran a clone of MS-DOS. Other software included a paint program, file manager, word processor, and spreadsheet. You could even connect the computer to a DOS PC and access its files remotely. They could also play Famicom games by loading them off of floppy disks into memory. There's more information here: https://helloacm.com/the-8-bit-dos-by-famicom-clone-bbgdos-i... . These days, BBK is better known for being the company behind the OnePlus and Oppo cell phone brands.