Is arm64-v8a compatible with armeabi-v7a?

For my Android-app I'm using the ABI "x86" and "armeabi" right now. The armeabi is used for all ARM-devices, including armv7a and arm64-v8a.

Now I would like to remove the "armeabi" and just continue with "x86" and "armeabi-v7a".

I haven't found any hint in the docs, that ARMv8 is also compatible with ARMv7 - can anyone confirm that my app will still work on devices running arm64-v8a, if I don't offer an armeabi but now an armeabi-v7a-library?

Many modern Android devices (i.e. Nexus 5x) have AArch64 processors with arm64-v8a instruction set. Both - armeabi and armeabi-v7a - libraries run fine on these modern devices. Therefore, we can assume the answer to your question to be 'YES'.

See this for a breakdown of ABI management on Android: https://developer.android.com/ndk/guides/abis.html