I went through 4 rounds on interviews. The first one was a regular HR phone screening, where I was explained that given that they had a number of different open positions at the moment, the plan was to run the process and find the best fit for any successful candidate.
After that, I had a video call with a Product Manager of the team. It took around 1h and followed the traditional PM interview structure. My advice: go read Cracking the PM Interview, it will give you a lot of useful tips.
Then I received a case to prepare. This was one of the most demanding steps. Without much knowledge of the market or the users, it was important to balance a bit of desktop research with reasonable assumptions. I had to submit a deck and it was assessed by the team before I was invited to the final round.
The final interview was a full day on-site. I had to present and defend my case. Then I met with the rest of the Product team (PMs and CPO), as well as a Product Designer, an Engineering Manager and the Head of HR. It was exhausting but they made it super easy, everyone was extremely friendly and open. I got the chance to ask about the transformation of the company and its future outlook.
Finally, and in parallel to the offer, I had a couple of calls more with HR and PM to review the roles available, which areas sounded more interesting to me and where they saw the best fit.
Overall, it was was a demanding interview process -- but extremely open and transparent. I grew more and more excited as we progressed. I took the decision to join based on the challenges and opportunities of the company, but specially on how keen everyone seem to find the best talent and team fit.