Actually, the version I have up on itch already is pretty minimal if you ignore everything except the "Save card as image" button. If you want to look at it it's https://robotface.itch.io/btcg-card-maker , I set it so you can see it with the password "decker"
Check the v character in the "Level" label in the top left of the card, for example
If you still want a minimal example I can provide that later today