Cerise is probably the most surprised since I think he would remember the program Sasha was originally a part of. He wouldn't outright ask about what happened that let Sasha become an actual person, but he would be very curious about it lol

Saph would be shocked that Sasha didn't just have an elaborate cosplay thing going on the whole time (and not fully understand how her being alive works), but she'd be fully supportive of her friend uvu

Astra doesn't understand and doesn't think she really is a robot lmao (she didn't know octolings were different from inklings until years after she met Saph and Cerise)