And yet, still the largest source of methane emission.

They also have the largest population. Per-capita they are not the largest source. It's ridiculous to evaluate countries' outputs without regard for the size of their populations.

As a product they can sell. Let's not pretend like this has some altruistic motivation.

That's true, and yet they also chose to massively subsidize their solar industry in order to meet climate goals.

Where is "the bad shit that China has done?" You still haven't said anything about this.