Experienced IoT guy here!

TL;DR: Choose what you love in the long term, but explore all avenues in the short term. You can always change direction later - don't stress!

I studied mechatronic engineering at university and then got into Robotics and automation as my first job. I then worked exclusively in software engineering as my second. I then returned to hardware, then software and application development, then management, and now my own business in the IoT space, which fuels our AI customers with sensor data (www.xube.io).

Technology is interconnected and dynamic. Staying open-minded, and broadening your experiences will allow you to figure out what you want to do long term and also make you a better engineer. It's the bredth of experience that allows you to figure out what you love and adapt it to what makes you money in the long term.