Exit interview questions/offboarding

Hello HR community! I wanted to ask you for some insight! One of our most valuable employees, who´s been here for over 10 years is leaving the company next week! Could you tell me a few exit interview questions for employees leaving the company? Do you have any tips and pieces of advice regarding offboarding?

I always ask about their experience in the company and the things that they would change! I find that as people are leaving they’re really not holding back and I can get some juicy details off them lol!