Also, I highly recommend NOT registering for Pan-EU unless you have to, because in reality most of your sales will come from UK and DE anyway. If you get any sales in the other countries, it would be good to analyze what percent of the business comes from those markets. France, Italy and Spain are very small compared to UK and DE on Amazon for most goods.
If you just register for German VAT, you won’t have to do so much admin work either.
But don’t let me stop you. I would just say be sure to analyze this stuff before jumping at a big endeavor (unless you already have).