Reddit reviews Soft Floor Hockey Puck (Set of 12)

I don't think you'll be doing yourself much good. It may help minimally, but the dynamics of shooting a tennis ball and hockey puck are different, especially if you're a beginner (which I don't know).

For example, elevating a tennis ball in a wrist shot would probably involve opening the face of your blade as you release. If you got into the habit of doing this in your wrist shot, it could negatively affect your form with a real puck.

There are soft rubber pucks available that may be a better option if you can't shoot a green biscuit/roller puck/hockey puck without causing damage. For your form alone, I think these would be better. Here is an example.