So, to be clear, Penny is fully sentient, yes? She has freewill and emotions?

Pretty much! As much as I don't like comparing my work to existing works, I'd say she's about on par with the T-800 from Terminator 2, still somewhat restricted by aspects of her base coding but not very much, able to make decisions and act outside of her initial programming, and learn new things and act upon new information.

The described course of events above does follow her path in her original body as well, though--surplus military bot, repurposed to be an entertainer. Copy her AI into an advanced military prototype because she volunteers for the task and it's less effort than coding a new military AI (although there's a possible plot hole in why they didn't just use Sable's AI or something instead, I can come up with a few possible reasons though), she decides to pursue a music career instead now that she can pass for a meatbag. It's sorta like poetry, it rhymes.

Wow. You've clearly put a lot of thought into this character, both in terms of backstory and how she generally functions. I am curious, when she speaks, does she sound like a normal person?

Thanks! You've probably noticed over the years that "tonal whiplash" is a recurring theme in my art, with some things being super fleshed-out but other things being "I just wanted to draw this lol". This concept fits into the former I guess.

Her speech does, in fact, sound mostly organic! As humorous as I find text-to-speech voices sometimes, with their awkward, stilted and sometimes flat delivery, there's no way she's going to attain stardom with that. I say "mostly" organic because she does sometimes have the occasional glitch, stutter, or random pitch shift.