An important point: don't see it as a "should I consider it or stay a BE developer?" kind of thing. If you accept the PM role, even if it means more money, the skill sets and responsibilities will be completely different so be aware of that too.
The primary benefit of doing this is that you develop a product and people-oriented mindset. All of a sudden, you are thinking about the "whys" instead of "hows". You think about customers and their pains and wants. This can be very rewarding if your natural disposition is to help others.
Technically, there's very little onboarding you'd have to do. Unlike programming, there's no language to learn, except English (or whatever language your business people speak). And by that I mean learning to speak the customer's language and using it to define the problem domain.
Long time ago, product managers (or business analysts, to be precise) would also use technical "languages" such as UML to describe the product. This fell out of favor in most industries. Agile mostly killed deep technical analysis (outside of code). It also killed use cases in favor of "user stories", which are a terrible way to describe a product in my opinion. But I digress.
Depending on your industry experience, you might have to do some onboarding in terms of understanding the market, customers, their purchasing decisions, and where do your company's products fit in all of this. I would start in an industry that you already know well.
All things considered, if you already have an offer and like it, trying on the product manager's hat will broaden your expertise and if you ever decide to go back to programming, this will be very valuable to you and your clients or employers.