Go on. If the "font" was attractive it would be worth applying time and effort into making it work.
Yes, it possible to multiplex different user-defined characters to achieve some form of bit mapped graphics.
It looks HORRIBLE on a regular LCD.
Multiplexing might work on an OLED because they have a faster response.
But since you can buy COG GLCD displays very cheaply it seems better to just use graphics. i.e. low power for an LCD, attractive fonts, available in transreflective, ...
The idea behind using multiple user characters is not unreasonable. In practice you seldom need more than 8 user characters at any one time. However the proposed scheme uses 8 displaying "012"