The health pass IS your vaccine proof. You need it to access transport, restaurants, and hotels. There are stories of people being allowed into restaurants by showing their passport and vaccine proof to staff, but staff in France are under no obligation to serve you if you don't have the official health pass. Even though I'm only going to be in France a few days, I thought it was best to get one. Mind you, I am flying into France, and the real issue is getting from Paris down south. If I was literally taking a bus from Spain into SJPP, turning around, and walking back to Spain, you may not need this.
The web based portal to apply is quick'n'easy. They want a picture of your passport, your travel ticket, and your vaccine certificate from home. The link for tourists is:
www.demarches-simplifiees.fr/commencer/passe-sanitaire-etrangers