Can one specialize as a cyber librarian?

All reference librarians use the internet today; there is no separate need for a “cyber” librarian category.

@janbb Sorry I mean having all of most books online?

In the future.

Not just internet.
Not just books.

Mainly online and digital resource material.

Where the library doesn’t have brick and mortar locations?

Sure that’s a possibility. During Covid my former colleagues worked from home, helping students find resources in databases online