Desktop (not application menu) icons for all users in Ubuntu 20.04

I have a machine running Ubuntu 20.04 and made a .desktop file. I tested it in my desktop and it worked, so i copied it to all existent users and did

sudo su; cd /etc/skel/; mkdir Desktop;
cp /home/MyUser/Desktop/MyIcon.desktop ./

So that all new users have access to the icon (the application is executable by all). However, when looking at what appears to other users, it is clearly not an executable .desktop file (comparison for what appears to my user and other users in images below).

what appears for my user What appears to other users

It seems doing what this answer suggests solves the issue, but i need to be the other_user doing this (where other_user is the user that will have the icon as an executable). So the only thing that can automatize the creation and correct configuration of the icon for new and existent users that comes to my mind is doing:

cd /path/to/other/user/Desktop
sudo su -l OtherUser
gio set app.desktop metadata::trusted true

for existent users and, for new future users:

cd /etc/skel/

and adding

gio set ~/Desktop/app.desktop metadata::trusted true

to .bashrc. This does not feel intelligent. Also, the sudo su -l option returns me an error:

gio: Setting attribute metadata::trusted not supported

Is there a better way for new users and a working way for already existent users?

Edit to add response to cbugk comment: content of file is in the form:

[Desktop Entry]
Encoding=UTF-8
Version=1.0
Type=Application
Terminal=false
Exec=/usr/local/path/to/executable
Name=Name of application
Icon=/usr/local/path/to/image.png

Answer based on @cbugk comments and the third answer for this question.

For some reason, even switching to user via sudo su -l or sudo su doesnt allow you to allow the launching of the desktop icon via CLI. I guess its some security reason, but not sure. Apparently you can use dbus messages to work around this and send the command indirectly. My way of doing it for several users and several desktop icons:

1. For all users that already have a desktop:

 cd /home/
 sudo su -l user
 cd Desktop 
 for icon in ./*.desktop; do desktop-file-install --mode=0755 --dir=$HOME/Desktop ~/Desktop/$icon; done;
 for icon in ./*.desktop; do dbus-launch gio set ~/Desktop/Telegram.desktop "metadata::trusted" true; done;

2. For future users:

cd /etc/skel/

mkdir Desktop; cd Desktop

(copy all my .desktop files to here and add the following lines to /etc/skel/.bashrc)

for file in $HOME/Desktop/*.desktop; do desktop-file-install --mode=0755 --dir=$HOME/Desktop $file; done

for file in $HOME/Desktop/*.desktop; do dbus-launch gio set $file "metadata::trusted" true; done

BE AWARE: item 2 will give permission for all desktop icons in user desktop to be executed every time the user logs in. This might be a security risk. I accept suggestions on better implementations.