Android Micro USB to DB9 Serial Adapter - Serial Cards & Adapters | StarTech.com
DigiSnap 2700 configuration via Android device | Support | Harbortronics
CQRobot RS485 or RS422 to USB Serial Communication Port Converter Adapter Cable. with FTDI FT232 Chipset, 300-921600bps Rate, 2.2 Meters, for Win7 / Win8 / Win10, ME, Linux, MAC, SCM, Android, etc. :
Coding USB-Serial using Android Studio
GitHub - mik3y/usb-serial-for-android: Android USB host serial driver library for CDC, FTDI, Arduino and other devices.
Arduino Android USB Serial Communication With OTG Cable : 11 Steps - Instructables
Is it possible to connect arduino pro with an android phone with a usb cable? - Electrical Engineering Stack Exchange
Android Things - USB communications
A dirty and quick example of serial port communication in Android | felhr85
USB Communication between Android and Arduino - The Engineering Projects
DroidTerm: A serial port terminal emulator for Android | felhr85
Serial OTG. Arduino CH340. FTDI. rkl099's Extension - Tutorials and Guides - MIT App Inventor Community
Amazon.com: ELECABLE USB Type C to RS232 DB9 Serial(9-Pin) Converter Adapter Cable 5ft with a Male to Female Connector, Compatible with MAC OS, Windows, Android, Linux Type C Device (USB C) :