@her_prof ho sry i dont know why i thought it does. So if you add sync in and out it will be even more interesting!!

@mackemint yea even without gate it will be awesome :-) and for the M8, yea of course I will buy one if I can (like everyone? lol) but (can have a but? I'm not sure, but if we have to say a but) i think I should prefer real gameboy buttons and gamepad than ones used on M8tracker. Gameboy buttons and dpad seems to haver better ergonomic but as i say if it was available i would buy one immediately...

What is this Fates?
I'm not very much into the whole modular thing, prefer trackers

Regarding RPi 4 - sure it's nice with quicker boot times but Piggy runs very fine on RPi zero. More resources doesn't equate better performance if the CPU meter peaks at 30%

M8tracker is a beautiful thing and I recommend everyone to get it, but it's gonna be considerably more pricey than this project. I bet Tim will be done with his launch before I get my act together, but one can't stress perfection.

The NerdSEQ thing looks Huge, way too big for my sensitive wrists haha!

Analog sync for LGPT would require rewriting the application, I'd recommend building a Teensy Arduinoboy, this way one can get a USB-MIDI+Analog sync in one device.

Polarity of MIDI minijack - great point!
The beauty of DIY is that one can customise their things to their liking. How to configure the standard of the plug should definitely be part of the build guide.

My dream device would be able to run SunVox too. The closest I've gotten to that is PocketCHIP but I still haven't figured out how to eliminate ALSA underruns on that thing.

m8 tracker does NOT have gate i/o, just midi i/o.

It would be interesting if you could also run fates on it:

https://github.com/okyeron/fates

Yea it's a great project and i'm sure there are many people interested in that. For my part I found a pi boy in my country and bought it. It's a gameboy raspberri with a real raspi, i mean, not a pi zero. I bought that because it has usb port on it but it's expensive and i don't know if it will arrive because my order is stuck in same place since 28th december with no news...

You have also pi43 which seems good, cheap, but is seems to be unconfortable and too big...

You have m8 tracker which will be released i think in the next months (but i don't know)

You have nerd seq portable which will be released this year too.

But keep working on your project! I can be interested too, and with midi/minijack port it's awesome! (if it works directly with catskull electronics midi/minijack stuff (gen mdm, ym2342, gba midi synth...) it's even better! I mean using only one mini jack. It's really frustrating when you have 2 devices with minijackMidi port but which needs minijackmidi + midicable + midiminijack to work...

If my pi boy arrive some day i will say if it works good. I plane to create a chiptune machine for that, select lgpt at startup or other trackers or music programms on emulator. If you want to boot directly on piggy and poweroff when quit i can help i did that on my raspberry pi (normal one, not the pi boy)

EDIT : also, you can consider adding gate in and gate out like on M8 tracker which will make possibility to sync with korg series and with lsdj + nanoloop (many other hardware machines works with that too like akai rhythm wolf).

I think this would be awesome!

What fully-featured handhelds are people using in 2020 for running LGPT?
I'm using a Circuit Sword by Kite. USB MIDI is great, a dedicated mini-TRS serial MIDI would be greater.
The sound chip is awesome. Based around a CM102S+ USB audio interface, it has a built-in Dynamic Range Control, aka a master bus compressor that can be used for fun and profit.
My main complaint about Kites Circuit Sword is that the shoulder buttons are placed inconveniently for my weak, carpal tunnely hands. Also, the audio volume isn't very loud out of the box and requires manual hardware hacking.
I'm considering designing a handheld with a Gameboy Advance SP form factor and I'd like to make check of interest check for a project like this with good assembly instructions.

The unit I'm envisioning would run on a Raspberry Pi Zero (or maybe even a Banana Pi M2 Zero if I'm feeling adventurous).
This would be available as a DIY kit requiring soldering and light GBA SP case modification.
It will run the RetroPie distro and boot directly into Piggy and will therefore be able to run a plethora of retro games if one wants to switch to LSDJ or when one wants to kill time in between beatmaking.

This unit would have the following features:
Dedicated RetroPie image, aka burn to SD card get piggin'.
GBA SP form factor requiring minimal case modification.
Audio jack with volume that can go loud enough for plugging into a mixer.
A master bus compressor that can be "pushed" by adjusting the Piggy project / sample volume.
MIDI in/out over USB and / or MIDI out via 3.5-TRS jack.
Safe shutdown
Project available as a guide for sourcing parts and how to assemble it.
Cost of approximately $100 depending on how you choose to source parts.

My questions to you:
Is this project relevant or is there already a unit out there that ticks enough of these boxes?
Would you prefer USB MIDI or UART MIDI?
Do you have any suggestions?
What are your unanswered questions?

I've read a couple of threads that seem to imply that there is a desire for this kind of device and I'd love to contribute something to the beautiful LGPT community out there.

Cheers