Chrome
Download Chrome if you don’t have it.
Add a shortcut to a website as an app
For Windows, Linux, and Chromebook users, you can add a shortcut to a website on the internet as an app in Chrome.
Open Chrome.
Navigate to the website you want to add as an app.
At the top right, click More.
Click More Tools.
Click Create shortcut.
Enter a name for the shortcut and click Create.
Once it is on your desktop, drag it to the dock and it with save it there.
Safari
Doing this in safari is not the best way to do this. It will not have a gmail icon pic so you will have to change it manually. It also will not let you put it in the dock.
How to Create a Desktop Shortcut to a Website Using Safari
Open the Safari web browser. You want to resize your browser so you can see your desktop.
Then go to the website you want to create a desktop shortcut for.
Next, select the URL in the address bar.
Then drag the URL to your desktop to create the shortcut.
Website with pictures below:
https://www.techbout.com/add-shortcut-website-mac-18223/
How to change Mac icons for apps, folders, and document
Open Finder and navigate to Applications
Click the app you’d like to change the icon for and use the keyboard shortcut command + I (or right-click and choose Get Info)
Have an image for the new icon you’d like to use, jpg or png often works best
Drag the image on top of the existing app/folder/doc icon (you may need to enter your Mac’s password)
You may need to close and reopen the app to see the change in the Dock (folders and docs should update immediately)
Website with pictures below:
https://9to5mac.com/2021/11/08/change-mac-icons/