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

app.intersend.io | 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.