How can I be sure that my SHA-1 key is populated properly in the Android app?

Question

I am in the process of implementing sign-in via the Google account in the Android app. Now I have the known issue of com.google.android.gms.common.api.ApiException: 10 when trying to sign in.

Most StackOverflow answers refer to improper SHA-1 key and advise to match it between local .gradlew signing report, google developers console, and firebase console. I did all of that, removed my SHA-1 and created a new one during the new build, made sure that it matches my local key store, Google Developer Console, and Firebase Console. Also, I hardcoded web_client_id and made sure my package name is the same in Google Developers and Firebase Consoles. Still doesn't work.

So the idea is maybe in within at the app SHA-1 key is not populated properly at the compile time? There is a known similar issue with the web_client_id which we need to hardcode. Web_client_id is populated from the same place where the SHA-1 key is stored: google-services.json file. Could you please help: How can I make sure that my SHA-1 is populated properly? How can I log my SHA-1 key at run time? Are there other ideas to solve this login problem? Below is my code for the sign in fragment class:

package com.exa.myProject.login

import android.content.Intent
import android.os.Bundle
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import com.exa.myProject.R
import com.exa.myProject.list.ListNonRespondedActivity
import com.exa.myProject.unsorted.Global.Companion.TAG
import com.exa.myProject.unsorted.Global.Companion.toastString
import com.google.android.gms.auth.api.signin.GoogleSignIn
import com.google.android.gms.auth.api.signin.GoogleSignInAccount
import com.google.android.gms.auth.api.signin.GoogleSignInClient
import com.google.android.gms.auth.api.signin.GoogleSignInOptions
import com.google.android.gms.common.SignInButton
import com.google.android.gms.common.api.ApiException
import com.google.android.gms.tasks.Task
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.auth.FirebaseUser
import com.google.firebase.auth.GoogleAuthProvider
import com.google.firebase.auth.ktx.auth
import com.google.firebase.ktx.Firebase

private const val RC_SIGN_IN = 100

class GoogleSignInFragment : Fragment(){
    lateinit var auth: FirebaseAuth
    var googleSignInClient: GoogleSignInClient? = null

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val gso = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
        .requestIdToken(getString(R.string.default_web_client_id_hardcoded))
        .requestEmail()
        .build()
    googleSignInClient = this.activity?.let { GoogleSignIn.getClient(it, gso) }
    auth = Firebase.auth
}
override fun onCreateView(
    inflater: LayoutInflater, container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {
    val view = inflater.inflate(R.layout.fragment_google_sign_in, container, false)
    val signInButton: SignInButton = view.findViewById<View>(R.id.sign_in_button) as SignInButton
    signInButton.setOnClickListener {
        signIn()
    }
    signInButton.setSize(SignInButton.SIZE_STANDARD)
    return view
}
override fun onStart() {
    super.onStart()
    val currentUser = auth.currentUser
    updateUI(currentUser)
}
private fun signIn() {
    val signInIntent = googleSignInClient?.signInIntent
    startActivityForResult(signInIntent, RC_SIGN_IN)
}
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)
    if (requestCode == RC_SIGN_IN) {
        val task = GoogleSignIn.getSignedInAccountFromIntent(data)
        handleSignInResult(task)
    }
}
private fun firebaseAuthWithGoogle(idToken: String) {
    val credential = GoogleAuthProvider.getCredential(idToken, null)
    this.activity?.let {
        auth.signInWithCredential(credential)
            .addOnCompleteListener(it) { task ->
                if (task.isSuccessful) {
                    Log.i(TAG, "signInWithCredential:success")
                    val user = auth.currentUser
                    updateUI(user)
                } else {
                    Log.i(TAG, "signInWithCredential:failure", task.exception)
                    updateUI(null)
                }
            }
    }
}
private fun updateUI(model: FirebaseUser?){
    val signInStatus = if (model == null) getString(R.string.user_not_signed) else
        getString(R.string.welcome) + model.displayName
        toastString(signInStatus)
    if (model != null) {
        val intent = Intent(this.activity, ListNonRespondedActivity::class.java)
        startActivity(intent)
    }
}
private fun handleSignInResult(task: Task<GoogleSignInAccount>) {
    try {
        val account = task.getResult(ApiException::class.java)!!
        Log.d(TAG, "firebaseAuthWithGoogle:" + account.id)
        firebaseAuthWithGoogle(account.idToken!!)
    } catch (e: ApiException) {
        Log.w(TAG, "Google sign in failed", e)
        updateUI(null)
    }
}

}