For small businesses, it would be very helpful to give the user/admin the ability to create a subnet then apply that subnet to a wired port of wireless SSID. Then select the PCI compliance mode this would apply both inbound and outbound firewall blocking rules to the selected subnet for the user/customer.
I happen to really look at the marketing pages and how it targets the retail space. Even in the photos, Meraki displays a payment device in one photo, security cameras in another photo, and a guest's phone in another photo. I know VLANs were just added to the app, but without firewall rules, standard user net traffic could hop onto the PCI network, video cameras could be compromised and find it's way onto the PCI network without the business's owner knowing.
I happen to find a chart comparing the MR to the GR and in that chart, it does state the GR is not PCI compliant which is fair, but those warning should be noted clearly in the product description. I am not picking on the products or want to come off as rude, but some missing critical information and marketing direction could lead an unknowing business owner in a pickle or unhappy with their purchase.