As someone who has been learning robotics as a hobby for a decade, my advice is: forget all the buzzwords and what the industry is using and start small instead.

I started robotics at a young age and began with small builds with LEGO motors and sensors, getting a feel of how each one works and how to interact with them with code. Then I got to much more advanced programs with LEGO Mindstorms EV3, learned about things like PID controllers practically and even started taking part in some competitions. Next, I went to writing actual code (as opposed to block-based programming) on microcontrollers like the micro:bit (and a few years later the Raspberry Pi Pico). I deepened my knowledge of how electronics work and learned how circuits work. I eventually got into a team with a few friends and we built a human-size robot combining 3D printing, a bunch of circuitry, ROS, 2 SBCs, Arduinos, a LIDAR and OpenCV for face/object recognition. This took years of learning step-by-step to achieve.

This is obviously not the path you'd take, robotics was what brought me into programming and you're probably going for the opposite.

You're not going to build a perfect robot or electronic device from the start and you shouldn't try to either. Get a microcontroller that's newcomer-friendly and play around with it. A micro:bit mostly emphasizes on the end result, with a built-in display and sensors and many plug-and-play modules to get you going. A Raspberry Pi Pico is much more flexible, but also requires you to learn about wiring and doing more things yourself. If you prefer coding in C, go for an Arduino. An ESP32 is also a good choice. It's a good idea to get a 3D printer and learn CAD in parallel, as it's a great way for a hobbyist to create actual tools that are more than a bunch of wires.

Once you get enough experience and confidence in your skills, you'll want to get into more advanced projects. Use your knowledge to plan them out, research and learn the technologies you're going to use (you can't learn everything beforehand and each piece of hardware is something different) and enjoy the journey from prototype to finished project.

And by the way (you didn't mention it but other comments here are so I'll give you an opinion on that), ROS is nearly always overkill for hobbyist robotics projects :D

I hope that helps you start your journey!