Sander no, also current generations of Apple Watch in combination with older iPhones, as iOS 13 is required for WatchOS 6+ installation, any owner with a Watch that is capable of WatchOS6 like S2, S3, S4, S5 but an iPhone which is not (with iOS 13) is also locked out, so bunq needs to rethink that entirely.
It's one thing for Apple to force iPhone device upgrades when a peripheral devices' software can't be updated with the current version, which Apple likes to do often, it's another for a company (like bunq) that depends on a lot of users using their features to do so too π