Hello, I have 8 years experience of programming.
I also have experience with IoT programming.
As for the project - one of the easiest ways to transfer data to the phone - the use of bluetooth module. For example, the HC-05 module has input ports for data transfer, so you do not even need a microcontroller if the data has a simple format.
If you need some kind of data processing, then you need to use a microcontroller. I like the microcontrollers of the STM32F0 series for simple tasks.
Please concact me if you have any questions.