I just pictured her with a crown on watching over her kingdom!! As far as getting him into her space- you will need to de-Winnie as much as you can. Of course you won’t be able to fully neutralize it but getting her scent off somethings will help. Use a water and vinegar spray on anything you can. While they are still separated you can take a blanket and put It in his cage for a day or two then put it in her’s so she can get used to his scent being in her area. Since she is free roam and doesn’t really have a “cage” I would suggest putting the blanket somewhere that she is especially fond of. Kind of like if there is one thing you expect to cause a problem when she needs to share it that is where you should put the blanket. that way she can get used to his scent being on it.
Other than that you’ve got the right idea. Once you feel confident leaving them along in a neutral territory then you can move SLOWLY into her room. Start with baby steps. When we introduced daisy to the condo we let her run around by herself in it. Bun kept wanting to go in after her kind of like saying “hey! be careful! don’t do that! that’s mine!” Once she came out we would let him go in to inspect and make sure she hadn’t messed anything up. You will need to let her call the shots. short sessions just like you’re doing now and take him out if she shows aggression. Another good tip someone told me is to take him out regardless of her behavior. For example set 15 minutes and even if at the end of the 15 she seems fine, remove pepito. This will keep her from getting to that point of annoyance and aggression. they called it “ending on a happy note” So essentially she wont ever hit that limit and get upset.
Good luck! you’re doing everything right so far!