Hmmmmm. Very interesting. It's really too bad that the US is not recognizing AZ as it is a perfectly good vaccine. It's also unfortunate that the promised Pfizer has not been sent. I hope things change very soon.
I myself am a mixed bag. I have had AZ and Pfizer and will likely get a booster in the form of Moderna soon.
If your first shot was a Pfizer, then your second one should be a Pfizer. Same with Maderna, and J & J is a single dose. Mixing vaccines is not a smart idea, nor is it condoned by the vaccine manufacturers or the CDC.