secrec > you are using HUNDREDS or THOUSANDS of pieces that individually wouldn't exist without megacorp somewhere in the background
I am pretty sure that's not what anyone means here, or can reasonably expect. At least I don't. Redhat and others are partly funded by corporations like Berkshire Hathaway, and their devs are paid with it. That reasonably means influence.
Debian is not at all similar to a megacorp, and does not pay devs anyway.
In real life, how much closer than Debian can a big group get to being uninfluenced by megacorps? Would you expect a group of unpaid volunteers relying on donations to make their own kernel, OS, and every single piece of software they add? Even Google doesn't do that, although they half-do with Android kernel and OS.
The guy behind TempleOS did, and it now belongs in a museum.