I really like the idea of [name_f]Soleil[/name_f] nn [name_u]Sunny[/name_u]. (But I’m billingual in English and [name_m]French[/name_m]). I think you could use any name that starts with [name_f]Sun[/name_f] or [name_f]Su[/name_f] and contains an N.
My first thoughts were [name_f]Sonya[/name_f] or [name_f]Sunniva[/name_f]. I prefer [name_f]Sonya[/name_f].