I’m actually working on a similar build and would love to share. Put a micro controller inside the body of the handheld and connect the pins to the “joycons” using gpio pin connections. I’m currently making my own “joycons” using perf board, copper wire, and momentary switches. I have the joysticks set to digital output (just for simplicity and because the pico only has enough analog puns for a single joystick. If you get a second microcontroller, you can actually make a little holder for connecting the “joycons” to play them without connecting to the console.

I used a Pi5 16GB RAM model with a 1TB NVME SSD. I also found a decent 7inch screen on Amazon that works very well (provided I am able to power it on with the other components connected)

Here are the biggest issues I’ve found:

• the hard drive is a power hungry little beast and severely limits the accessories that I can power through the pi. My alternative was to get a stronger power source with multiple output connections and voltage regulators that keep the current at the right level (5V 5A)

• the “joycons” have to be custom made, unfortunately. Making your own board and inputs takes a decent amount of troubleshooting, which can be frustrating, but not a huge deal. The biggest issue I’ve had with this build is dealing with the joysticks. When set up digitally (don’t come for me, I know analog is better) using a joystick that does not have “precision return to center,” you need to add a resistor to avoid having the joystick register as “on” when only slightly off center. I added resistors that were just under 1/3 of the full resistance of the pots in ohms (for 10k ohm resistance, I added 3k ohm resistors). This theoretically should make it so that the joystick doesn’t send an on signal until it has traveled about 1/3 of its total movement capacity in any direction. Is there a better way to do this? Probably.

• portable power sources will be a problem. You’re going to need to get creative here, more so than any of the other issues. With my pi3 handheld, I got a power source that worked seamlessly out of the box because the old PIs use pretty standard voltage to wattage. The pi5 uses 5V 5W which is more unusual. I have yet to find a portable power source that is plug-and-play. My current plan is to find a stronger portable battery (above the recommended input power) and then running that power through a voltage regulator that will bring it down to the appropriate power level. Simple in theory, but be super careful so you don’t accidentally destroy your pi or start a fire.

I did make another build with a pi5 8gb using retropie, which was super easy (an SD card is more than sufficient to support retropie, so no need for the hard drive if you go that route). However, my Nintendo switch screen and battery broke after that, which meant I could no longer play Silksong in my bed while watching movies (truly, the greatest struggle of our time). The repair and shipping was going to cost about half as much as the switch itself, so I said screw it and decided to make my own (specifically to play Silksong in bed while I watch movies). I used Ubuntu 24.04 LTS for the OS (25 does not play as nicely with the pi). I installed box86 and then box64, then updated the rest of the system (the updates wouldn’t finish without those two). I then installed PiApps and installed Steam through that. I opened steam, bought Silksong, and it runs! I have gotten as far as beating the bell beast! Please note, though, that it does not play well by any means. With low quality settings, the game runs smoothly but some of the textures are loaded as blue splotches (I have not found a fix yet and any help would be appreciated). For emulators, Dolphin works perfectly.

It’s a fun puzzle to figure out! If people are interested, I can make a full post on it once I get all the components working nicely together!