Some examples of the time (often 7x8) https://www.nesdev.org/wiki/Fonts
Another open source example for 8x8 and 8x16 is GNU Unifont
You can go down to 5x5 for upper case while still being readable https://www.dafont.com/5x5-pixel.font
Looked at the topic in the context of silk screen printing with normal steel mesh.
Some examples of the time (often 7x8) https://www.nesdev.org/wiki/Fonts
Another open source example for 8x8 and 8x16 is GNU Unifont
You can go down to 5x5 for upper case while still being readable https://www.dafont.com/5x5-pixel.font
Looked at the topic in the context of silk screen printing with normal steel mesh.