At IST you can take more than one mobile, but no power-banks or hard drives. A USB charger would be fine, but there is nowhere on the A320 to plug it into. The search at the gate is very thorough, including a pat down.
I also had a trip to BEY and back this month. Had to pack the laptop at BEY. Happy to report it was fine! Staff at check-in were advising what is and is not allowed. There is a search when entering the gate area which is thorough and chaotic. There was a growing collection of power banks on the table, having been seperated from their owners.