✍️If this is your first time developing Shopify apps, my advice is to start with the smallest idea, using the technology you are most familiar with. Complete MVP in less than 1 month and try to get first user.
I have many friends who spend a few days configuring servers, optimizing system costs. The customer doesn't care that, at the first stage, PAAS and 5 minutes of deploy is all. I choose Heroku and dedicate my time to customers and services.
Removing the payment tier and just being free is definitely not a good strategy to compete with your competitors. When you're at a premium price point, it also proves that your app is good enough to deliver with a more premium customer segment.