BLE connection issues with Android / Nordic

Hello all.

I am new here, clearly, and working with Arduino for the first time.

I'm currently running the battery monitor program on my BLE Sense and attempting to connect to my Pixel 2 running Android 9. I'm watching the serial monitor as I connect it, and the Arduino does make a connection, then begins sending the battery voltage to the serial output. However, the phone remains in "attempting to pair" status which times out, killing the connection.

I downloaded the Nordic nRF Connect app for Android and that works (yes!)

Ultimately, I'm working on a custom Android app that will receive sensor data from the Arduino. I'm concerned whether or not I'll be able to establish a BLE connection via my app. I have not found much information about any BLE (specific) libraries I can/should use in Android Studio, or much information related to connecting to an Arduino BLE.

I'm a complete Arduino noob, some Android experience, plenty of programming background in other realms. Any guidance on making this work seamlessly from the Android side would be much appreciated.