You said:
Building a commercial product on top of a free open source software is pretty awful practice
But as @Deleted said, a lot of stuff you use daily is based in some form on FOSS. Linux was just one big example.
I agree that building a commercial product on top of FOSS without giving back in some form is pretty awful practice. But the bold part is important. Simply taking something that’s free and open source and using it for your commercial product is not bad, it’s more common than you might think. But if you do that, you should give something in return.
If I’m not mistaken Tagesschau reported that the organizers planned 10.000 people to attend. Let’s say the 160k is a high estimate I think it’s safe to say there were around 100k people so ten times more than originally planned. It’s a huge win after the past few months and years where most protests in Germany were right wing protests.