My intent is that the project could be used to build your own device(s). The proof-of-concept script(s) can just be dropped onto a 'bare-bones' Pico.
If you want a more fleshed out solution, you could look at 'PiShop' (my go-to supplier up here in Canada-land).
For example: Pico, Display, Charger, Battery
There needs to be some electronics to 'buffer' the audio signal in-to/out-from the Pico. My intent is to create a small PCB to do this. The above display is cheap and has both a SPI and I2C interface, it's connections are as follows:
Which leaves the 'South' end of the Pico usable for LTC connections. My code uses separate PIO blocks and each has it's own input/output pins. Once designed my LTC interface card will need to buffer audio and connect into the Pico.
One obvious variant would be to build a Digi-Slate, which should actually be pretty easy... There are spare pins on the Pico (pins 1 tru 7) which can be used for I2C and GPIO. I'll make a pledge to add appropriate connector to the next PCB.
Adafruit makes a large (1.2inch) 7-segment display and back pack: https://www.adafruit.com/product/1264
And there's this library which is capable of driving it: https://github.com/smittytone/HT16K33-Python
There are some other Pico like boards, with displays already attached. It really should be trivial to adapt the code for these, just remember that in-order to achieve high FPS the code should be structured to send a few bytes to the display as possible.
I've started experimenting with a super-cheap display based on the SSD1306 chip-set, checkout the 'alternate_displays' branch
If you do use my code for a personal project, drop me an email/picture. If you make a device to sell, please send me an sample to test.