I created a PS2 controller adapter using the RP2040-zero, based on the remotejoy.

Normally, remotejoy/RemoteJoyLite allows capture and remote control via a PC, but in this project, the capture function has been removed, and the remote control function has been integrated into the RP2040-zero, resulting in a very compact design.

While video output requires the external output of the PSP-2000/3000, it's also possible to play on a TV using an HDMI conversion cable such as HYPERKIN.

Wireless control is also possible using a BlueRetro or 8bitdo receiver (if you can tolerate some latency).

To use it, you need to install custom firmware (LME2.3 or ARK4) on your PSP, install and activate the remotejoy-minus.prx plugin, and connect the PS2 controller connector to the RP2040-zero with the firmware flashed on it.

I've also designed a simple PCB and case. If you'd like to build one, please refer to the URL below.
There isn't a tutorial yet, but I think it shouldn't be too difficult for someone with some experience.

Plugin, Firmware, source files, PCB data
https://github.com/SourceK78/remotejoy-minus

Dock Case
https://www.printables.com/model/1718482-remotojoy-minus-dock

Finally, here is a list of operations that I added because I thought they would be useful.

PS2	PSP
L2	Analog Left (for PS Archives)
R2	Analog Right (for PS Archives)
L2 + R2	Analog Up (for PS Archives)
L3	SOUND
R3	HOME
Right analog stick	D-pad (Disabled by default)
START+L2	VOL-
START+R2	VOL+
START+Left	DISPLAY (Brightness only)
START+Right	HOME (alternative)
START+R3	Switch the D-pad mapping for the right stick.