That area of software is very advanced at this point and even at FAANG you're mostly just wiring together services/libraries.
You might think "Well what about huge scale services?, that must be interesting?" Eh, not really. It just means more partitioning of data/traffic, more hosts, and more time writing pipeline/automation code.
I would recommend finding a more niche area you are interested in, for example: game development, game engines, image processing, machine learning, operating systems, graphics, VFX, audio/DSP, high performance computing, GPU related stuff, embedded systems, robotics, etc...