How is the fintech scene in Southeast Asia?

Pretty fragmented, every country is kinda different from the rest. I'll comment on payments.

Singapore is leading, followed by Malaysia and Indonesia probably, though Indonesia still has a very large unbanked population.

Singapore is small, and nearly everyone there is banked and using digital payments. Credit card usage is very common.

Malaysia is pretty fast with the adoption of e-wallets and digital payments, and cryptocurrency activity in the country is slowly rising. Debit/credit card usage is high, but not as high as Singapore's. Most of the rural areas still prefer cash.