As far as big corps go I think the BBC is probably one of the safest in terms of worries about monetisation. I'm not saying they're perfect but it's very different to if it was Sky or another commercial channel.

I don't see any real risk of corporations monetizing the fediverse.

Just look at something like Linux, which is a massive project that is both monetized by corporations while still remaining free, open, community-driven and accessible to just about anyone. I can't say the risk is 0, but it's certainly not large.

But I thought we went here to get away from the public web services where they monetized everything and put ads and tracking everywhere?

Why would we want this place to become the same? We can just open a web browser and we are in that ad infested place again.