My final solution to show Android keyboard thanks to Helios Alonso and Square team

focusAndShowKeyboardBySquareEditedByEgemenHamutcu.kt

fun View.focusAndShowKeyboard(tryAgain: Boolean = true) {
    /**
     * This is to be called when the window already has focus.
     */
    fun View.showTheKeyboardNow() {
        if (isFocused) {
            post {
                // We still post the call, just in case we are being notified of the windows focus
                // but InputMethodManager didn't get properly setup yet.
                val imm = context.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
                val isInputMethodManagerSetup = imm.showSoftInput(this, SHOW_IMPLICIT)
                if (!isInputMethodManagerSetup) {
                    // InputMethodManager still didn't get properly setup yet even we post the call.
                    // so we should give it one more try.
                    if (tryAgain) {
                        this.focusAndShowKeyboard(false)
                    }
                }
            }
        }
    }

    requestFocus()
    if (hasWindowFocus()) {
        // No need to wait for the window to get focus.
        showTheKeyboardNow()
    } else {
        // We need to wait until the window gets focus.
        viewTreeObserver.addOnWindowFocusChangeListener(
            object : ViewTreeObserver.OnWindowFocusChangeListener {
                override fun onWindowFocusChanged(hasFocus: Boolean) {
                    // This notification will arrive just before the InputMethodManager gets set up.
                    if (hasFocus) {
                        this@focusAndShowKeyboard.showTheKeyboardNow()
                        // It’s very important to remove this listener once we are done.
                        viewTreeObserver.removeOnWindowFocusChangeListener(this)
                    }
                }
            })
    }
}