A prebuilt APK is now available for Android. You will need a device with armv7 (32-bit ARM), AArch64 (64-bit ARM), or x86_64 (64-bit x86). 64-bit is preferred, the requirements are higher for 32-bit, you'll probably want at least a 1.5GHz CPU.
Download link: https://www.duckstation.org/android/duckstation-android.apk
Preview/beta download link: https://www.duckstation.org/android/duckstation-android-beta.apk
Changelog link: https://www.duckstation.org/android/changelog.txt
If you have an external controller, you will need to map the buttons and sticks in settings.