DumbDisplay Android app is a simple Bluetooth Classic / Bluetooth LE / USB Serial Terminal (monitor / plotter), extended to act as a "dumb" display (as well as a little bit of inputting means) for Arduino / ESP8266 / ESP32 / Raspberry Pi Pico -- using the DumbDisplay Arduino library (https://github.com/trevorwslee/Arduino-DumbDisplay)

The idea of using DumbDisplay as a display is that you can defer connecting real output gadgets to your microcontroller board until later stage of your experiment.

DumbDisplay can be used as virtual output gadgets in place of the real ones
• LED-grid layer
• LCD layer (text-based and graphical)
• 7-Segment-row layer
• Plotter layer
• TomTom Map layer
• Micro:bit-like layer
• Turtle-like layer

Microcontroller board can connect to DumbDisplay Android app via
• USB (OTG)
• Bluetooth (with HC-05 / HC-06)
• WIFI (for ESP8266 / ESP32 / Raspberry Pi Pico W)
• USB via DDWifiBridge (a Python program)

In addition to acting as a virtual output gadgets, DumbDisplay can route user "feedback" (like clicking) to microcontroller program with it's layer "feedback" mechanism. In other words, DumbDisplay can be treated as very simply input gadgets as well.

DumbDisplay also features the "tunnel" mechanism that aids microcontroller program to
• get simple data (including simple JSON data) from the Internet
• download image to your mobile phone, for displaying on a graphical LCD layer
• request certain "service" (like getting GPS position and doing object detection via TensorFlow Lite) from your mobile phone

Notes on DDWifiBridge:
* DDWifiBridge is a simple Python program comes with the DumbDisplay Arduino library
* Proxying USB connection to your desktop, DDWifiBridge bridges between USB and WIFI connection to DumbDisplay
* This way, there is no need of Arduino UNO to have special add-on in order to connect to DumpDisplay wireless via WiFi

Hope this little app helps.