Ich schreibe jetzt mal in English :-) I tested instant SEPA between 1822mobile (belongs to 1822direkt / Frankfurter Sparkasse) and bunq. Sending from 1822mobile to bunq (single test, cause it costs 0,99 Euro :-( ) is instant as espected with immediate push notifications... dont forget bunq is lightyears ahead :-).... and vice versa it didnt work as instantly from a pure user experience but the reason wasnt instant SEPA nor bunq, it was the 1822mobile app. The 1822mobile app is close to crap. It is not able to update transactions as well as balance in realtime itself nor by forcing it manually. Could be 20-30 Minutes, could be 5-10 Minute or hours on weekends. They know the problem already, dont know how long it will take to fix this.... cause there are so many other bugs, you cant even imagine. So I went to the ATM, pick up my iphone and send an instant to the 1822mobile account, quickly sticked the card into the ATM slot and checked my 1822mobile balance directly with the ATM... and there it was... right balance, money was there as fast as the other way around. So its often not the RT1 connection, its the account / app backend at the german bank or the "display of the account action", the app.
I tried with a friend of my, he is having a DKB account. It worked but also displayed it with a few minutes delay. I guess its also the app or the webend that cant quickly follow the account action. Never tested it withe Deutsche Bank... maybe they are better due to the more advanced app.
The latest iOS Sparkassen Mobile App, the app that all Sparkassen use in Germany, recently got updated to version 5 which finally was able to send / receive Auslandsüberweisungen (foreign money transfers, even foreign SEPA...) I guess this should now work with bunq instants out of the box. Its still quite funny that german banks or Sparkassen still view SEPA transaction no matter regular or instant crossing the german border as "Auslandsüberweisungen". Its usually no problem to active "Auslandsüberweisungen" in the banking app but its a bit inconvinient and feels like soft SEPA discrimination. ;-( Dont forget if you send more thant 12 500 Euro cross border in Germany (in or out) you need to call a Bundesbank telephone number even as a private user to inform them about the transfert due to statistical reasons. As far as I understand they could fine you if you doesnt.