there are some bugs in the repo - but it worked

[MarcWeber]

socat_buildscript_for_android.sh
-> then out/Makefile -> add openpyt.o at some lines.
If you compile on m1 (OSX) you have to add

${ANDROID_NDK}/build/tools/make-standalone-toolchain.sh \
 --ndk-dir="${ANDROID_NDK}" \
 --platform="${ANDROID_PLATFORM}" \
 --install-dir="${OUT}/toolchain" \
 --system="darwin-x86_64" \
 --arch="armv7" \
 || exit

in out/Makefile set AR and RANLIB to out/toolchain/bin/* versions

Compliation still fails, but there is socat. exe.

I succeeded with android-ndk-r9d