No they are not a scam. You should also be able to order the food without a visit, it just has to be approved by your vet.
Long as you are having yearly checkups done they shouldn’t have an issue approving your prescription food orders when they come in. Give your vet a call and hopefully you should be able to work something out.
I ordered an OrangePi 3 recently for pihole purposes and it has been great, it’s also probably overkill for this use but hey it was actually in stock and not terribly expensive.