How do you fetch content navigation for only one specific level

[ColtHands]

Lets say I have folder structure:

content
content/docs
content/docs/intro.md
content/docs/how-to-use.md
content/docs/api
content/docs/api/getting-started.md
content/docs/api/openapi.md

How would I get result only for children for a docs: ['intro', 'how-to-use'] and for api: ['geting-started', 'openapi']?

I can't seem to query this neatly