I'd also welcome informed views on Chinese participation at COP26.

The Chinese always appear reluctant to enter into aspirational international agreements that would freeze their disadvantages. This is true of arms control, but it also is true of climate agreements to limit fossil fuels. Apart from coal resources, and maybe the China Seas, they are also subject to the whims of international markets for energy. They are well aware of the problem of pollution, and lead (?) the world in the amount they spend on research into renewable energy. But they absolutely prioritize uninterrupted economic growth.

Apart from the international public relations aspects of Glasgow, why agree to timelines and standards that will depend on energy prices set by markets dominated by cartels--and which western countries are likely to bend or break if the necessity arises? I imagine that some degree of paranoia about the West's intentions to limit China's growth plays into this.

I don't think I'm unduly cynical about anyone's motives. There's a global recognition of the problem of climate change and real goodwill among countries of the West. It would be quite another thing if the Chinese didn't also recognize the problem and if they weren't devoting a lot of resources to solving it. They have set their own timeline for carbon neutrality, I believe.