If your product consists mainly of a HTTPS service with some particular Internet accessible fully qualified domain name, say https://benth-app.customername.example/ where your customer owns customername.example then it's possible already today although you should ensure the customer is told what you're up to of course.

If your service doesn't provide HTTPS or customers don't have it accessible from the public Internet then you'd need cooperation from them unless you yourselves control the DNS records involved.