Seeedstudio XIAO-RP2040 ( V1.0 ? ) - More than enought I/O and memory for this project. And can be used with Arduino C/C++ ( default ) or Python ( Micropython / CircuitPython ). Plus, it embeds two leds : 1 RGB pixel and 1 green smd.
Multiport 15pins micro-usb ( aka Sony S2 ) - micro-usb "classic" 5 pins and ( not on the same raw in the plug ) 10 additional pins of the Sony Multi-terminal Protocol.
This plug can be found on the Sony RM-VPR1. this remote have W/T zoom and movie record buttons and is fully compatible with my camera ( Sony ILCE-7M2 / " A7II " ). It's a good start.