Nvidia released Nemotron 3 nano recently and I think it fits your requirements for an OSS model: https://huggingface.co/nvidia/NVIDIA-Nemotron-3-Nano-30B-A3B...

It's extremely fast on good hardware, quite smart, and can support up to 1m context with reasonable accuracy

I second this: I have spent about five hours this week experimenting with Nemotron 3 nano for both tool use and code analysis: it is excellent! and fast!

Relevant to the linked Google blog: I feel like getting Nemotron 3 nano and Gemini 3 flash in one week is an early Christmas gift. I have lived with the exponential improvements in practical LLM tools over the last three years, but this week seems special.