Don’t bother with the cert if it’s not your job, but at least look into CCNA Routing and Switching. There are tons of courses available, both in person and online, as well as numerous YouTube videos on the subject.

See if your local library or community college has an adult education center that provides a course. At some point, you will need to learn subnetting, which is just math, but practice makes perfect, and your life is easier if you have it committed to memory.

Proper written work is still one of the most effective ways to do this.

Sorry if I’m about 10 years behind Linux development, but how does Docker compare with the latest FlatPak trend in application distribution? How you have described it sounds somewhat similar, outside of also getting segmented access to data and networks.