We are 50% ecommerce and 50% POS. It applies to both. And any app, as already highlighted, allows you to manipulate the discount codes at the cart stage but not at checkout.
In regards to rewards, we use Smile.io. It is an automated solution via discount codes. We do not issue them manually and there is no gift card issue option with them.
Again, not POS specific. The POS has a crap ton of limitations and issues so we are well aware of what Shopify is and isn’t. We have been with Shopify for over 10 years.