Thank you for giving a try earlier. I haven’t tried Docker method before. I will give it a go and will report back my findings.
Meanwhile, I was trying another approach by attaching the tf_text dependancy when building flex_delegate by adding it on the /tensorflow/lite/delegate/flex/BUILD file. I was trying to replicate what thisisjoshstone 1  did for building the benchmark tool.
tflite_flex_cc_library(
    name = "delegate",
    additional_deps = ["@org_tensorflow_text//tensorflow_text:ops_lib"],
    visibility = ["//visibility:public"],
)

This is along with copying some other tf_text dependent libs into the ‘/third_party’ folder.
I got a compiled aar (monolithic) from this way. However, I got the following errors when android is trying to load the library.
2021-08-07 03:36:58.736 4845-4845/com.example.android_tflitetest E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.android_tflitetest, PID: 4845
    java.lang.UnsatisfiedLinkError: dlopen failed: cannot locate symbol "_ZN10tensorflow14ResourceHandle14ANONYMOUS_NAMEE" referenced by "/data/app/~~2bQNIzfI7nLL_ZRsoniNzw==/com.example.android_tflitetest-cQfuuYwEt3pqiLamMpM8Sg==/lib/x86_64/libtensorflowlite_flex_jni.so"...
at java.lang.Runtime.loadLibrary0(Runtime.java:1087)
        at java.lang.Runtime.loadLibrary0(Runtime.java:1008)
        at java.lang.System.loadLibrary(System.java:1664)
        at org.tensorflow.lite.flex.FlexDelegate.<clinit>(FlexDelegate.java:61)
        at java.lang.Class.classForName(Native Method)
        at java.lang.Class.forName(Class.java:454)
        at java.lang.Class.forName(Class.java:379)
        at org.tensorflow.lite.NativeInterpreterWrapper.maybeCreateFlexDelegate(NativeInterpreterWrapper.java:511)
        at org.tensorflow.lite.NativeInterpreterWrapper.applyDelegates(NativeInterpreterWrapper.java:476)
        at org.tensorflow.lite.NativeInterpreterWrapper.init(NativeInterpreterWrapper.java:88)
        at org.tensorflow.lite.NativeInterpreterWrapper.<init>(NativeInterpreterWrapper.java:66)
        at org.tensorflow.lite.Interpreter.<init>(Interpreter.java:287)
        at com.example.android_tflitetest.MainActivity.runTF(MainActivity.java:74)


... and more ...

A check on my test android project’s minSdkVersion is 21 and  targetSdkVersion is 30 , which is consistent to my configs done during ./configure.
Using nm command on the .so file reveals the _ZN10tensorflow14ResourceHandle14ANONYMOUS_NAMEE   is an Undefined symbol. I’m currently stuck down here, pretty much trying without knowing entirely what i’m doing . I’m still working out what’s missing.