General APK install guide
In order to sideload and install APK files, you'll first need to unlock the vehicle's infotainment system (head unit). There are numerous guides online on how to do this. Perform a search on "BYD unlock infotainment DiLink" and there should be numerous guides on how to do so. If you prefer to have it done for you, BYDGear offers this as a service. You can reach out to BYDGear on his Carousell listing here.
Use this guide as the standard installation flow after obtaining APK files from trusted sources.
Obtain the APK from the official project page or another source you trust.
Download the APKs onto your phone or PC. If you have already unlocked side-loading, you can also download directly from a browser on your BYD infotainment system.
Copy the APK to the BYD head unit using USB storage or your preferred local transfer method.
Open the file on the head unit and approve installation from trusted sources when prompted.
Open the app while parked and grant only the permissions required for normal operation.
Record the working version number in your own changelog before updating.
Avoid installing unknown APKs from random mirrors. Treat sideloading as a deliberate owner modification.