u can't be onchain if you aren't online 

avici w/ data top ups

(sinbad iirc is only other wallet i know of w/ data top ups rn)

https://apps.apple.com/in/app/avici-buy-bitcoin-with-upi/id6465962039

intersend.io | via sequence. pimlico. poap. polygon. consensys. paxful. flipside crypto. dash. bridgewater. darpa. secdef. navy. dia. linktr.ee/alexanderchopan

i test the apps. but i can’t do the UPI part.

is it available outside india? In india every smartphone have at least 1/2 UPI Apps. BHIM UPI/ PHONE PE/ GOOGLE PAY/ PAYTM UPI/ AMAZON PAY/ and all BANKS have their own.

yeah. Almost everyone has it. Most popular way to send payments, no one uses banks anymore. 

also, its only available in Singapore and UAE internationally rn.