While Snappy Checkout does not restrict businesses and/or products, you'll need to follow the Terms of Service for PayPal/Stripe since all payments you collect through Snappy Checkout are deposited directly into your personal PayPal/Stripe account. See the links below for a list of restricted business types and products.

PayPal Restricted Businesses: https://www.paypal.com/us/webapps/mpp/ua/acceptableuse-full
Stripe Restricted Businesses: https://stripe.com/us/restricted-businesses