Apple - Is it a good practice to create a desktop shortcut on mac?

I would say desktop alias creation at install time for an app is an anti-pattern and bad practice for developers to implement as default behavior.

• The desktop belongs to the end user and macOS is designed to install apps for every user account and to consider more than one user per computer. To accomplish this, you’re either escalating the installer to root privileges to change multiple desktops or you’re ignoring / short cutting the way apps can (or possibly should) get installed for all subsequent users.
• The launchpad and dock and spotlight / Siri are the bespoke app launch tools and idioms so you can assume your customers are very familiar with how to start an app they just chose to install.

The most kind way to do this would be to onboard the user and ask if they want any shortcuts the first time they launch the app. Apple recommends you have a very light onboarding, so even this is against "best practice" but I would see it as the best way to make an alias if you feel it's the right call for the majority of the users of your app.

I would encourage you to read over the HIG - Human Interface Guidelines and the many free WWDC videos on app packaging and installation - your question is a good one and thinking how people see your app during installation is super helpful to make your app succeed with many customers.

• https://developer.apple.com/design/human-interface-guidelines/

This answer was written before the clarification that the OP is from a developer perspective, not end user

I've always been firmly of the school of "nothing on the desktop" personally - but each to his/her own.

You can find apps to launch in one of at least 6 ways...

• The Apple  Menu > Recent Items

• The Applications folder itself

• LaunchPad

• Spotlight

• Drag the App to the Dock

• Double-click any document & the relevant app will launch, or right-click Open With > for a list of alternatives which can handle that document type.

So many alternatives that it doesn't feel necessary to clutter the desktop with another.
However, it's your machine - do as you wish ;-)

No. You should just copy the app to /Applications (or ~/Applications), and let the user choose if they want to create a shortcut in the dock or somewhere else.

A lot of the time, "installers" in macOS are just disk images (dmg files) containing the app itself and a shortcut to the Applications folder. The user can choose to drag the app there, or anywhere else.