I stumbled upon a question in the PowerApps forum on how to make Gallery items clickable so I tested it out and found that it can be achieved very easily..
1. Create a gallery and bind it to Account entity in CDS..
2. Bind your Gallery to table with with a field that stores hyperlink. In this case I bind it to Account entity and field by the name of Website.
3. Select a text,label or image in the Gallery Item. On the On Select property, enter the following command
(Substitute website with the field that stores the URL)
In this case, I entered it on the Image.
4. Click save and Publish.
Now on the app, when I click on the image, it will redirect me to the website stored against the hyperlink.