Pretty easy - the HR screener didn't even ask me any questions, just set up a call with the Hiring Manager. After a super quick (10 min call max) I was brought in for a final round - about 5 hours. Despite meeting everyone under the sun, it was pretty easy day as it was clear that out of everyone I met with only one person had any clue about the job they were hiring for. Certainly in dire need of an SME. Which possibly could be a red flag because if no one understands your position you might not get the buy-in you need on the job. But there is always a chance they would let you run free and build as you see fit. But no way to really know unless you get in there. Tough call.
I never heard back on a decision. After weeks I reached out (and then waited again for awhile) and was finally informed the position closed without hiring anyone and they were going to use a consultant. It clearly didn't work out because less than 3 months later they are looking again for an in-house hire. I don't think management knows what they want/are doing. Wouldn't apply again/go down that rabbit hole personally.