Emile Hi Emile, bunq supports the Instant Payments networks TIPS and RT1. See more info here: https://together.bunq.com/d/40305-instant-payments-across-europe-with-tips
As for Dutch banks, not all of them are reachable through the instant payment networks that bunq is connected to. You can find more information here: https://www.betaalvereniging.nl/en/focus/instant-payments/participating-banks/ That is the reason why depending on the bank, sometimes you won't be able to send and/or receive Instant Payments from them.
However, when you send/receive money from other European banks, then most of the time you should be able to use Instant Payments because they're a bit further ahead when it comes to supporting TIPS and/or RT1. Hopefully all Dutch banks will soon have full support for TIPS and/or RT1 to get full instant payment coverage through The Netherlands.