Need advice - fostering a pregnant colony cat

I will start by saying that the rescue I work with does not spay/abort. I’m hoping that’s something I can convince them of. That being said, I was asked to take in a pregnant cat that had been trapped in a colony about an hour from me and I have had her for a week. I have her set up in my home office with me with places for her to settle and feel safe while she adjusts to being indoors and gets used to my presence. In my opinion, I don’t believe she’s fully feral. She’s either somewhat comfortable with people because there were several people caring for her colony OR she had a home at some point. She will hiss softly once or twice if you’re close, but no growling or attempts to scratch me. I think I’m making progress with her because (just today!) she would lick creamy treats off my finger. Other than patience and gently petting her while feeding her, any tips for helping to determine if she can be (re)socialized? I’m out of my comfort zone here. I usually take in spicy kittens trapped during TNR projects. I have never had an adult. I have to establish enough trust that she will let me handle the kittens when born to socialize and get them vetted. Any suggestions?