ChromeBook - how to start a terminal application by clicking an icon

Question

Chromebook with linux enabled, but not developer mode

Version 119.0.6045.209 (64 bit)

The following works fine in the terminal

cat /home/martin/helloworld.sh:

#!/bin/bash
echo Hello World
sleep 10

-rwxr-xr-x 1 martin martin 36 Dec 11 13:46 helloworld.sh

martin@penguin:~$ ./helloworld.sh 
Hello World from home
martin@penguin:~$ 

I would like to invoke this application by clicking on an icon on the desktop (or in the taskbar).

I have tried different settings within a .desktop file (with or without menulibre)

#!/usr/bin/xdg-open

[Desktop Entry]
Version=1.1
Type=Application
Name=HelloWorld
Icon=applications-other
Exec=/home/martin/helloworld.sh
Terminal=true

I can invoke HelloWorld, which ChromeOS sees as an application. A terminal window appears, briefly containing ======== (a message from linux?), before immmediately going blank. The terminal window does not close.

I have also tried

Exec=/usr/bin/python3 /home/martin/helloworld.py

Which starts python (good!), but ignores the python file (not good)

Python 3.9.2 (default, Feb 28 2021, 17:03:44) 
[GCC 10.2.1 20210110] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> 

I have restarted the computer a number of times.

Instead of using .desktop, would it be possible to just have a link on the desktop - how would that link be executed? So, a link to helloworld.sh which would automatically be executed in a new terminal window.