I guess it depends on the region. E.g in China QR codes (and similar codes) were widely used more than 10 years ago by hundreds of millions of people on a daily basis for payments, ordering at restaurants, apps sharing or social media.

Just Use Postgres for Everything Startups use too much technology. My advice: Use Postgres for everything

What languages/framework are you going to use it with? I would bet you'll thank yourself for switching to Postgres instead of MySQL at some point. Have you read www.amazingcto.com/postgres-for... ? :)