OLED

Driver chip and bus determine which library you write against, not the physical size. A 0.96inch SSD1306 and a 0.96inch SH1107 look identical on a desk and need different code.

About 30 parts: monochrome I2C modules from 0.49 to 1.3 inches, SPI/I2C grayscale and 65K-color RGB panels up to 1.5 inches, a transparent OLED, and ecosystem-specific units for Raspberry Pi, FireBeetle and M5Stack Grove.

• The 0.91inch 128×32 and 0.96/1.3inch 128×64 monochrome modules are the most common sizes: DFRobot's Fermion 0.91inch uses an SSD1306 over I2C, M5Stack's 1.3inch Grove unit uses an SH1107 — same dimensions, different driver libraries.
• Waveshare 0.96inch (B) and 1.3inch (A)/(B) boards expose both SPI and I2C; the 1.5inch 128×128 modules add either 16-level grayscale or 65K-color RGB (SPI only) depending on variant.
• The 1.51inch Transparent OLED (128×64, SPI/I2C) draws light-blue pixels on see-through glass; the Xadow 96×64 RGB OLED is built on an SSD1331 driver — not interchangeable with SSD1306 code.
• Adafruit PiOLED 128×32 plugs directly onto a Raspberry Pi header; FireBeetle Covers OLED128×64 stacks on DFRobot FireBeetle boards; Gravity and BOSON units use plug-in connectors.