Would this be an idea? I would use sheer curtains that you can push aside to not obstruct the view, but they will dress the patio doors.

That looks nice - I also like the light fixture & rug you used! I had thought about very sheer ripplefolds all the way around .... thank you!

Maybe some panels on either side of the windows and door and a round carpet under the table and chairs to give a sense of definition.

I would use roman shades on all the windows and slider dressy but not really in your way and can be closed in the evening to avoid the black hole effect and a new chandelier with some color in it and I like the idea of a rug but they are sometimes hard to get big enough and still have looking right in a bay.Can't really get a sense of colors from the space but here are some ideas I would for sure use some pattern for interest

If you go rug shopping, look for a rug that wide enough to have the chairs comfortably on them, even when you pull them back to sit down. Generally that is at least 24" wider on all sides of the table. Your table is oval I think? But because your room is angled I wouldn't opt for a rectangular rug. So either round or oval I think.
If you go for a drum pendant, it will be nicely echoed in a round rug.

Here's an ideabook, follow the link under the picture.
https://www.houzz.com/magazine/10-tips-for-getting-a-dining-room-rug-just-right-stsetivw-vs~32442746