How do I add a Home button to Safari on iPad?

Sorry, no, not possible.

iPadOS Safari doesn’t have any concept of the traditional “Home Page” with which you may be familiar when using a desktop or laptop computer. As such, a Browser “Home Button” (returning to a Home Page) has no conceptual meaning within the UI - as employed by iOS/iPadOS Safari.

Maybe another solution is:

Open Safari on Iphone, go to google.com then add bookmark that site to favorites. Drag the icon to the top left. Finished!

Each time you click on the adressbar you will see the icon of Goggle in Favorites. Press and it will works like as return to homepage.

Apps from different Software Developers may have different features and capabilities. As these widely vary, you will need to make your own comparisons.

Firefox for iPadOS does have a kind of Home Page, that is presented upon opening a new page/tab, but this does not replicate the desktop functionality with which you are making comparison.

The OS Paradigm fundamentally differs between the environments that you are attempting to draw comparison.

I hope this information and insight is helpful to you.