BlueRetro, a multiplayer Bluetooth controllers adapter for PS1/PS2 consoles, is an open source project based on darthcloud. It uses the popular ESP32 chip.

Suit for PS1/PS2 Consoles to PS3/ps4/ps5/Xbox One S/Series X|S & Adaptive controller/Wii & WiiU Pro/Switch Pro & Joycon/8bitdo Wireless Controller

Blueretro Upgrade Firmware  Tutorial

Blueretro  Firmware (V1.8.1)

Blueretro  Firmware (V1.7.3)

Blueretro Quick Start Guide