This is a list of eDP display controller boards, with their parameters and some notes on each specific board. More boards will be added as I buy and test them.

a. HDMI-only board with flashable resolutions

• Chip: RTD2556
• Power input: 12V, 5.5-2.1 barrel jack
• Audio: 3.5 output
• Resolution: depends on firmware
• eDP connector type: 30-pin

These boards are typically available cheaply ($12/piece) with 1080p firmware flashed in.

b. HDMI+VGA board with flashable resolutions

• Chip: RTD2556
• Power input: 12V, 5.5-2.1 barrel jack
• Audio: 3.5 output + speaker output (onboard amplifier)
• Resolution: depends on firmware
• eDP connector type: 30-pin

There's different variations of this board floating around, some have additional connectors that can be soldered to if you'd like to embed the board in a project. You can switch between the VGA and the HDMI ports using the buttons.

c. HDMI-only board with jumper-adjustable resolutions

• Chip: unknown
• Power input: 12V, 5.5-2.1 barrel jack
• Audio: none
• Resolutions: 1920x1200, 1920x1080, 1600x900, 1366x768, 1280x800
• eDP connector type: 30-pin

This board has an IR remote, for whatever reason - it doesn't seem to have any extra functions that the physical buttons won't give you.