The vast majority of software on Google Play is absolute spyware-laden slop. There are turstworthy apps, sure, but they are drops in an ocean. F-Droid’s trustworthy-to-ad-ridden-slop ratio is pretty much definitionally lower than Google’s, by virtue of it being actually curated. That everything on it is libre and they are working hard on reproducible builds just makes it all the better.
This is a bunch of opinion though. I'm not saying I disagree, but I do think it's bad faith to state as fact what is opinion. Is Play a "walled garden" or is it not curated? It can't be both depending on what suits the argument. You may disagree with the policies, but suggesting there are no policies in favour user privacy is just false. You may think they aren't enforced sufficiently, but again this is opinion. The policies are there.
F-Droid has the benefit that it essentially doesn't have to deal with malicious actors. It's very easy to have a high quality library when there are no malicious actors.
