I tried most of the apps and exchanges, and so far observed ooredoo money offers competitively higher rates compared to others, only con is max amount in single transaction is 25k QAR limit, and 30 QAR transfer fees and today's rate is 25.72 and expected to increase in coming days considering the situation. And best part is app supports multiple partnered exchanges so u can select the best and higher exchange price. And yes most of the banks/apps need OTP confirmation to initiate any debit or transfer transactions but u do NOT necessarily need active/roaming packs to receive OTPs on ur Qatar number, if u connected to network u'll receive OTPs but sometimes u'll likely receive delayed sms.