Even the one mentioning that pets eat 1/5th of the worlds meat and fish production? or have an environmental footprint equivalent to 2 4x4 cars? (in the reference)

That car fact is in a quote by a guy with a company selling a meatless pet food alternative. I’m going to need an valid source, not a financially motivated comment to a journalist.

Your other links don’t hold up much better. The cat ones advocate for keeping domesticated cats indoors. The dog article isn’t about pets either, but roaming packs of strays. I doubt you have to try very hard to convince anyone that stray dogs are a problem.

Pets eat 1/5th of the world meat and fish production, do you want sources for that (easy to google)? Do you understand this fact alone show how large their environmental impact is? Do you still see an evil conspiracy behind those facts, and why?

I agree with you, but it's kind of like pointing out how much destruction and suffering is involved with our factory-farming of meat: Nobody wants to hear it right now. Try back in 50 years.

I think the issue is at least partially a failure to present an alternative vision.

People do the things they do and consume the things they do in order to meet some need (stimulation, entertainment, pleasure, etc.). Although, I don't think it's unreasonable to advocate for some austerity, to a significant degree people are going to need alternatives that meet the needs that were formerly met by the things they are giving up.

It seems to me that environmentalists tend to fail to provide a vision for what those alternatives could be.

We may need to reconsider what is austerity also, is living without a pet austerity? is washing ourselves with a soap bar instead of a multitude of cosmetic products and stuff austerity? is eating local legumes/fruits austerity? is using a bike to commute or go shopping austerity? etc.. There are many environmental-friendly alternatives, I think it's every person's role to find those alternatives (politics are more interested to foster consumerism), this guy is quite inspirational https://www.youtube.com/watch?v=nX4kq4QfYRA