I like the idea. My startup started with managed hosting. We use to provide subdomains of customer.company.com domain for each customer to quickly onboard users. Later, when the customer was ready to move to their own domain, we had to ask them to setup A records or provide DNS credentials. The tech stack wasn't too hard for us but hand holding each customer to get the custom domain working was the pain point.

* Will AutoSSL also provide a way for the customer to login and provide them instructions on how they can setup the domain on their side?

* Some of our customers had CAA records preventing LE from working. This is about informing the customer that this record exists and what the possible alternatives are.

* This was mentioned elsewhere but AutoSSL is a cPanel feature. So, I would consider rebranding.

* What are the proxying limitations? Does it support Websockets? How much load can it handle?