I recently read the word "mainstream" as a verb and doubted whether it was the best choice in the sentence. Can you say you want to "mainstream" something? Perhaps it is grammatical but just unadvisable?
There's nothing technically wrong with "verbing" any noun you feel like, as long as your listeners understand you.
Personally, I tend to consider it a red flag that the speaker doesn't really know what they are talking about, and are trying to cover up that fact by throwing impressive-sounding jargony words at me. So doing that as an attempt to impress me is not liable to work out well for you. But I can't speak for anyone else.
Mainstream has been used as a verb in print since 1973 (and possibly before), which means that it appeared in speech well before that. In a general sense the first citation they have is from 1982 and that used “scare-quotes” so it was a new sense then. But it’s thirty years old now, although that may still be too new to be universally accepted.
Whether it is the best choice in any particular sentence depends not only on the hearer’s view of its acceptability but also on the sentence itself. You haven’t quoted anything in the question.