Except even if you want some kind of loyalty token, why do you need a blockchain for it? Are you going to let users... mine coffee loyalty points? Do all of your coffee customers need to verify the integrity of the count for all other customers on a ridiculous bit of software?

Just create a db table called ledger and +1 | -8 it when they buy a coffee or use the reward.

I was excited about blockchain too, right up until I became a blockchain dev and realised about an hour in to the job that the whole thing was a dead end. The requirement for blockchain to be useful is that literally everything in the world happens on one giant monochain. Without this, smart contracts are useless for anything other than gambling on the chain about the chain. The second you leave the box - all of that POW is for nothing.

The perenial question is "why not just use a database in that case, since you're the entity controlling the currency anyway?"