Steel-barred windows - Who offers them?

Hello dear community,

due to the difficult situation of acquiring land, we are still somewhat far from our house building project.
Nevertheless, I have been dealing with the topic for quite some time.

Among other things, at the top of my wish list are sash windows, specifically those that were previously installed in industrial buildings and courtyards. I have attached a picture, although this is already the modern version, installed in an architect's house in Hamburg.

Regarding my problem: The windows targeted are usually made of steel, which allows for very delicate processing. However, steel naturally acts as an optimal thermal bridge.
Therefore, I am looking for companies that offer thermally separated steel windows; so far, my search has yielded:

Montastahl
a small company in Berlin
and, I believe, MHB Stahlbau

Do you know of any other companies? Have you installed such windows yourselves and have experience or can you say something about the costs?

And then I am also looking for alternatives in the aluminum sector. Here I often find the look somewhat "bulkier," but maybe I can't avoid it. As a last resort, I would also forgo the sash windows. Then there is a wide range on the market. But first, I try to aim for the optimum ;)

Among other things, at the top of my wish list are sash windows and [...] In the worst case, I will even do without the bars.

I don't quite get it: sash windows are very important, if necessary even without the bars (? ? ?)

Yes, they are very high on the priority list. But if it’s not possible, for example due to no good compatibility of design/functionality or energy loss or possibly an unjustifiable additional cost, then they have to be removed from the list. I wouldn’t make my house construction dependent on that now ;) But, as I said, they are at the top of the priority list and we would also like to invest more money in it, within our means, and for that give up other things or increase the budget.

For me, no contradiction. But that’s not what this is about now. I am very grateful for all tips/experiences and will report accordingly if I have any news on this.