This model is the smallest I could make it, and has been designed around Micha213's PCB (https://github.com/Micha213/BlueRetro-PS1-2-Receiver).
What to order:
Requirements:
In order to reduce its length, bend the pins behind the PS2 plug upwards.
You can use this custom jig to cut the two parts of the PCB: https://www.printables.com/model/427837-ps1ps2-blueretro-pcb-cutting-jig
The author marked this model as their own original creation.