Generally, if a provider supports SEPA Instant payments then TrueLayer supports these payments as well.
However, in KNAB's case, while they claim to support SEPA Instant payments, some of our clients using Payouts in the Netherlands have reported that payouts to KNAB accounts are not being sent instantly.
We believe the discrepancy between what KNAB claims and the reality is due to these payments not being domestic (i.e. NL IBAN to NL IBAN). We are looking into this with KNAB directly but for now we don't expect these payments to be sent instantly.