I've been going through the process of getting my car listed as ULEZ compliant, wrote to Porsche around a month ago and then received the Certificate of Conformity about a week or so ago, emailed the details along with the 1st and 2nd page of my V5C to the Clean Air Zone department, Low Emissions Zone Scotland and TfL, the Scottish department emailed back less than 24 hours later to say my details had been updated and my vehicle is now listed as compliant, and having just checked the Clean Air Zones website it seems to also be fully compliant for that as well, however TfL replied to say that they couldn't confirm all the details as they need all 4 pages of the V5C!
The other odd thing is that I didn't bother applying for a new V5C as its a £25 fee for a new one and I didn't really think it was necessary, but today despite not applying or paying for one I received a new updated V5C in the post with my NOx level now listed! 🤔