Advanced Operating Systems

You could try to do "systems" stuff...especially distributed systems. Might require some higher level/more hardcore classes though. I'd say check out advanced OS, advanced networks, advanced databases type classes. Then finding jobs may be slightly trickier because like you said, web dev is more ubiquitous. You can try to find similar students at school though and see where they go after graduation or for internships.

Something kind of like what I'm talking about https://www.udacity.com/course/advanced-operating-systems--ud189

I heard these two courses were good -- and they're free

https://www.udacity.com/course/introduction-to-operating-systems--ud923

https://www.udacity.com/course/advanced-operating-systems--ud189

https://www.edx.org/professional-certificate/dartmouth-imtx-c-programming-with-linux

You have the option to audit (take for free) the individual courses that make up the series.

https://www.class-central.com/course/coursera-introduction-to-embedded-systems-software-and-development-environments-8458

https://www.udacity.com/course/advanced-operating-systems--ud189

https://www.udacity.com/course/introduction-to-operating-systems--ud923

https://www.udacity.com/course/gt-refresher-advanced-os--ud098

https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-828-operating-system-engineering-fall-2012/

What about some classics like Uncle Bob talks?

A lot of good design focuses on decoupling and creating components which work together but separately also.

Id first look into language agnostic design principles such as SOLID

https://youtu.be/TMuno5RZNeE https://youtu.be/zzAdEt3xZ1M (golang)

A good book will help.

https://www.amazon.com/Clean-Code-Handbook-Software-Craftsmanship/dp/0132350882

I still keep a copy of the Gang of Four book at arms reach even tho the popularity is dwindling as OOP is not topic of most convos today. However when dealing with DI and sharable components in Golang, i find myself still falling back to abstract factories patterns. Its a good breathe of knowledge to at least glimpse at the patterns here: Design Patterns: Elements of Reusable Object-Oriented Software https://www.amazon.com/dp/0201633612/ref=cm_sw_r_cp_api_i_7BzvDbXJC5WS4

Once you get thru these topics, you can start picking up what I consider the "hot" architectures of today: Microservices, event based systems, domain driven design, event sourcing, and architectures aiding themselves to functional programming.

I really enjoy reading Martin Fowler blog posts: https://martinfowler.com/tags/application%20architecture.html

He covers a lot of these topics.

PS: maybe a niche and a personal favorite of mine but ive learned ALOT by researching the different types of kernel architectures. Nothing really geeks me out like those topic, but not for everyone.

A fabulous free course exists on these topics: https://www.udacity.com/course/advanced-operating-systems--ud189