Ubuntu: what have I missed below?

I’m thinking about core Ubuntu skills for a developer working on a Ubuntu OS, that is, he/she needs to be comfortable with Ubuntu. Would the following list suffice? What have I missed?
Many thanks.

Know file/directory structures etc.
How to install new software ( ie. apt-get install or apt install or even snap on occasion… )
How to create and edit files ( gedit, pico, vi is too cryptic … )
How to manage file permission ( chmod etc. )
Understanding executable file or shell script ( .sh )
And maybe, how to manage user account as well ( adduser … )