$1 Club, page-2114

I found this from an older Muslim, talking about installment payments:

"You can buy things on installments. It is perfectly halal. It is the same as buying against delayed payment. The evidence for this is as narrated by Al-Bukhaari (2068) and Muslim (1603) from ‘Aa’ishah (ra) that “the Prophet (saw) bought some food from a Jew to be paid for later, and put an iron shield in pledge for it.”It is also permissible that price to be paid on installments be more than that for full payment. It comes under the general permission of trading and is agreed upon by the four Imams."

Also, BNPL has been implemented in Malaysia already which is predominantly Muslim. I thought about this a few weeks ago, it seems like the consensus is that BNPL is all good to go in Muslim countries.