Garlic and Greek yoghurt are easy to get. Just dried garlic mixed in the water will do, nothing special.
Supermarkets will stock electrolyte mix or you can make your own if you google it for the proportions. They should also have ACV in the healthfood aisle but don't sweat it if you can't get it.
Chicken vitamins are probably only available at the feed store or you can order online. Liquid Vits for human babies can be used instead.
Its a good idea to get some of this stuff anyway, as essential home chicken remedies if any of them get ill or seem off in the future. It just helps to boost their systems and fight off an illness, restore good gut flora, etc.