Merchants are not aware of card-based installments and those...

Merchants are not aware of card-based installments and those that do simply do not know how to enable the feature on their POS device.
Introduce FI Paylater and the card issuers will enable it for them ( to keep in the market and not let pure BNPL take away sales during the purchase) with the added capability to pay the merchant upfront.

This is good timing leading upto Christmas after a dozen or so banks start to implement and look at whats happening to those 3 banks currently testing the feature in readiness to golive.

Good find @Louie2