not building x86 is up to the developer, the default according to the native sdk

The default behavior of the build system is to include the binaries for each ABI in a single APK, also known as a fat APK. A fat APK is significantly larger than one containing only the binaries for a single ABI; the tradeoff is gaining wider compatibility, but at the expense of a larger APK. It is strongly recommended that you take advantage of either App Bundles or APK Splits to reduce the size of your APKs while still maintaining maximum device compatibility.

At installation time, the package manager unpacks only the most appropriate machine code for the target device. For details, see Automatic extraction of native code at install time.

so if you use the apk from your phone it may or may not contain an x86 compatible binary.