Hishyār
Hishyār means 'alert', 'vigilant', or 'sober-minded' in Persian and related Iranian languages.
Yes. Hishyār is used in Persian- and Kurdish-speaking Muslim communities; it is a cultural-linguistic name rather than a Quranic name.
There are literary and regional attestations of the adjective and its use as a personal name in Persianate sources; it is not tied to a widely-known single historical figure in mainstream Islamic historiography.
Common pronunciation in English transliteration is 'hi-SHYAR' (with the second syllable stressed).
Yes. It carries positive semantic connotations (awareness, prudence) and is a scholarly, uncommon choice with Persian cultural roots.