Can you get a ceramic coating from a mobile service?
You can get ceramic coating from a mobile service. But just because you can, doesn't mean you should. Not all detailers are of comparable skill level, and not all ceramic coatings are made equal.
All the top brands only sell their products to professionals, and all of them require the detailer to be accredited. This includes them demonstrating the required skill level and proving that they have a suitable environment to do the work. None of them would give accreditation to a detailer that worked mobile, unless they can bring with them a mobile workshop where temperature and humidity can be controlled. Such things do exist, but it's still not ideal.
Although it is not a perfect correlation, it tends to be the case that the more difficult a coating is to work with, the better the quality. This shows at the bottom end of the market, where products that are very forgiving and easy to apply are not that durable. There are companies that make products like this for supply to dealerships where the skill levels of their technicians are generally not very high, and they are not blessed with the best facilities to work in. This goes down even further to user-friendly retail products, which are not even comparable to professional ceramic coatings.
As always, you should choose a ceramic coating based on the reputation of the detailer, not the brand of the coating. But in this case, you should research that too. The general rule of thumb is, if you can buy the product yourself, it's probably not a professional quality product.