?cheapest/"best" setup for chromakey passthrough

[derpomcderp]

Hi all, great looking product! I'm keen to use chromakey passthrough for a flight sim. The main priority is minimising lag between the real-world action and the display of it in VR. I understand a Quest 3 would be the best "bang" for one's buck (sold with minimal profit margin), but meta don't share access to the pixel stream so that's out. Does anyone have strong feelings about which headset/headmounted-camera work best for chromakey passthrough?

I'm leaning toward a bog-standard cardboard-viewer with a mobile phone in it for the display, and a Zed Mini for head-tracking & passthrough... But I'm happy to be told, if anyone thinks that's a terrible idea, and they have a proven solution.

Thanks for any time and consideration anyone feels able to give this,
Derpo