For very small stuff, OLED displays are another possible alternative. Great contrast, and there's no backlight so you don't spend power on the "off" pixels. Yo

For very small stuff, OLED displays are another possible alternative. Great contrast, and there's no backlight so you don't spend power on the "off" pixels. You could start with SSD1306 (monochrome, 3.3V) and SSD1331 (16-bit color, boosted voltage required). They speak I2C and SPI, and have decent software support. The cheap and cheerful ones are <=1" diagonally though, so you need to step off the happy path to find badge-sized ones.