Yes only GBG with those two (last I checked). I went with Andersen 100s, with exterior and interior grilles, and they look incredible. Cheapest option and by a significant margin if you order from HD. I'd recommend the casements over the SH version. Could have been my install but the action on the SHs are pretty wonky. Action on the casements is perfect.

Very classy and distinctive, and appears to be well-built out of heavier gauge metal. While I find light fixtures to often be overpriced, I think that particular one (at about $900) does not seem to be unreasonable. Since the manufacturer is a brand name known for high quality, the likelihood that you are going to find this somewhere else for more than half off is remote, unless it gets discontinued and you find a deal. You don't say what your intended purpose is for this fixture, but I will point out that it uses a single 60W bulb, so if this is for use in an area where you need more light, you should think about that.

What are the requirements? Tall? Transom over door? Or is it just the style of the door for a normal size front door?

There are regular storm doors now that have self-storing screens, so that you can switch functionalities without having to move a section up and down from the basement. "self-storing" is what you want, and there are various ways that it can be done. https://custom.homedepot.com/custom-doors/p/EMCO-200-Series-1-2-View-Self-Storing-Storm-Door/306553462/51112-Single-Door/29401-36-x-80-in/29383-White/30006-Anytime/29394-Clear/29697-Black/50561-Standard/7202-No This one has a permanent screen and a piece of glass that can move up or down; I had one with all glass, but you could pull down a handle that extracted a (rolled) screen and pulled it into place. All sort of magical. https://www.homedepot.com/p/EMCO-36-in-x-80-in-400-Series-Sandtone-Universal-Self-Storing-Aluminum-Storm-Door-with-Nickel-Hardware-E4SN36SA/204946250#overlay (you may need to watch the video to see what I mean)