@Qbish Wide Sargasso Sea is a somewhat different animal, imo. For a start, Antoinetta/Bertha was locked away against her will by Rochester. She had no agency over her marriage and as a married woman was completely in his control by law. The feminist message in WSS is borne out of that struggle. Also, we know little of Bertha's background from Jane Eyre, so Jean Rhys was able to use a lot of poetic licence to create a back story.
If the intention of H&M was to tell Miss Haversham's story prior to her non-marriage, it's not likely to be that interesting or feminist. Unlike Bertha, we know Miss. H's story, because Dickens wrote it. She decided to marry, against advice, a man who swindles her, so she's a bit dim/lovesick/wilful. Miss Haversham may have been jilted, but she was freed of male control as a result. Rather than embrace her freedom, or indeed seek out a true love, or restore her reputation, or replenish her fortune through using her wits, she chose purgatory. Nobody locked her away - she chose that path herself. And she also chose to live a life in suspended animation, and to emotionally torture a young girl, Estella, and subsequently, Pip (child abuse is not feminist).
She barely saw anyone once she locked herself away. H&M would have to completely throw Dickens' character as we meet her in GE out of the window to make an interesting character we would like and consider a feminist, and to justify the subsequent "life" she made for herself up to the point we meet her in Great Expectations. They'd have to turn her into Batwoman or something, crawling out of the window in disguise, seeking out the fiancé and brother who swindled her, and in the meantime, fighting crime and saving urchins and prostitutes on the mean Victorian streets, before returning home at dawn, slipping back into her wedding dress and single shoe, and moping about the house (because, of course, that's the best way to deflect attention from the true identity of Victorian London's lone lady crime-fighter).*
*That's my idea, H&M, if you are reading this, copyright.