Business analyst, project manager, commercial manager and presales engineer are often effective feeder roles into product management.
Working on your own projects is the simplest option. Find a tech project that appeals to you, look up a PM guide for beginners, and get started. There are many persons who can offer advice and criticism. PMs must continuously innovate.
It might be as easy as building a website. What technology stack will you employ? the front or the back? Hosting? DNS? What qualities do you require? Etc.
Additionally, you will require technical training, whatever that entails. You don’t need to be an engineer, but you might become anxious if I ask you to create a MySQL query or integrate with this API. the fundamentals of the internet.
The issue with volunteering is that the business has little stake in the outcome. I would have no time for volunteers because I hardly have enough time for my direct reports. Nobody deserving of their weight would have the time. If you choose to choose that path, start off as a project manager until you have the necessary experience to manage a product.
What if you did a side project of your own? Being ‘CEO’ of a side hustle is basically being a PM (probably learn more than you would as an actual PM too)!