Hi Frank, I too have been waiting for responses API to become available, but with Azure. I'm sorta suprised more people haven't been asking for it. In one of their first blogs about it in early August, Azure said they would be making responses API available to gpt-oss but I am yet to see it.

If it's any consolation, I did find it is supported on Cloudflare. I have tested it with gpt-oss-120b along with their Autorag implementation and it was working well. However, it does have a lot of limitations such as rate limiting, restrictions on file size for RAG etc, but it might suffice for you PoC.