Who is considered the “seller” from a tax law perspective if the creator mints its NFT through a third party platform?

From a VAT perspective it is quite decisive whether a seller allows buyers to mint over his own
website or via a third party platform. German VAT law prescribes, in simple words, that the one who
is perceptible to the outside for selling is responsible for VAT. Hence, generally speaking, if A and B
are working together in order to drop an NFT, A becomes responsible if they sell it in over A’s
website. If they decide to sell it over B’s website, B is responsible.