ARIA make reader read non-focused element content

I have elements on a page which are "focusable" (buttons, elements with tabindex etc) and screen reader reads the content just fine.

However, I have some other elements that are not focusable (due to the fact there are lots of them - dropdown list results etc), so I don't want user to click tab countless times, but they are navigable through left/right/up/down keys, and they get CSS class "selected" (although some other element - their parent - is actually focused)

I want to make reader read those specific elements, with the class "selected". How do I do it?

(I tried applying attribute aria-label="read this" to them, but it didn't work; it works only if element is actually focused)

from ARIA make reader read non-focused element content