I wouldn't pay much attention to the "partners" listed on that site. I think it's just to give a general overview to those who know nothing about it that you can pay on- and offline at many merchants.
What I find puzzling is how Apple can be so lacklustre on updating the country pages with the supported banks and the support document (see here:
https://support.apple.com/en-gb/HT206637): They went to the trouble of creating A-Z lists for the US, adding Banco Mediolanum in Spain, squeezing in N26 in the UK without sticking to sorting by A-Z and HSBC in France, then left out a big bank like BNP Paribas (France), Hello! bank (France) or the big Monese launch. Very odd overall...
And it also goes to show that banks might launch at any time, even those that aren't listed - such as Monese yesterday. Revolut should hopefully go live soon.
What also might be interesting is the fact that 1822direct (belongs to Frankfurter Sparkasse) announced the upcoming support of Google Pay on Twitter today (and see here:
https://pay.google.com/intl/de_de/about/banks/). Hopefully Apple Pay is on the cards. With DKB, BW Bank (rumoured Apple Pay launch in Spring) and 1822direct we would have three banks belonging to the Sparkasse group. Great!