I would pronounce it see-AHH-nuh (soft A sound), like how I’d say [name_f]Kiana[/name_f] or [name_f]Liana[/name_f]. [name_f]My[/name_f] second guess would be shaw-nuh.
[name_f][/name_f]I slightly prefer [name_f]Siana[/name_f]! I like [name_f]Alessa[/name_f], but prefer the similar [name_f]Alessia[/name_f].