The Email template has the following Liquid objects available:

{{product}}
The product title that the customer subscribed to
{{variant_name}}
The variant option title that the customer subscribed to
{{customer_name}}
The name the customer filled in when subscribed

The SMS template has the following Liquid objects available:

{{product_name}}
The product title that the customer subscribed to
{{variant_name}}
The variant option title that the customer subscribed to
{{customer_name}}
The name the customer filled in when subscribed
{{shop_name}}
The Store name in your setting information
{{product_URL}}
The short link to the product page, can be tracked status as checked when opened