Finding out in advance whether a prospective employer has insurance that covers bariatric surgery, much less revision bariatric surgery, is not easy. You don't want to signal that health insurance is an issue with you, especially before the offer. You have a right to ask, of course, but asking may be a turn-off before an offer. You're probably going to have to rely on the information you get from the careers page on their website, and then HR when you go in for an interview - which means going through the process. And not being too detailed in your questions until after the offer - at which point, you can ask for copies of the available medical, dental and vision benefits, "so you can compare with other offers."
Or you can ask someone you KNOW who works at the company.
Or you can ask someone you KNOW who works at the company.