Interesting, is this one just for Pfizer as I've had Astra Zenica which I believe is a different set of spike protein DNA sequences?

This one's for the nucleocapsid protein. If you'd like to test antibody generated by the vaccines, you'd have to take the Anti-sarscov2-S test.

All currently used vaccines use the same version of the spike protein sequence.

Incorrect. Pfizer, Moderna, and J&J use a pre-fusion stabilized sequence. AZ does not.

However, all currently used vaccines are just the spike (S) protein plus possible non-COVID proteins (in the viral vector vaccines), so none will induce antibodies against the COVID N protein.

I imagine it might be possible to guess whether someone was vaccinated with the AZ vaccine based on whether they have antibodies that are specific to the site that’s modified in the stabilized sequences. I don’t think anyone does a test like that.