You can make up to 200 gallons of wine at home if your aren’t going to sell it. That’s more than 1,000 bottles.
If you go commercial, Maine’s liquor license will determine what you’ll have to do to get your facility up to snuff. Installing lots of sinks was one thing I remember we had to do. R.A.S. went through this more recently so maybe they have insight on build-out.
The federal bonded winery application has quite a lot of questions about the location, physical space, water and wastewater. It wasn’t fun but it doesn’t cost anything (a small winery doesn’t have to buy a bond, despite the title).
Also you need to have a certificate of operation if you are in a city.
These three things have to be done before you start making wine and it can take six months or longer, especially if you need to upgrade the garage or barn.