P: Use AI to improve faces, and ideally entire images, in noisy RAW images photographed in low light.

I have used Topaz Upscale AI in Photoshop a few times. It can also improve faces, but the result is usually awful. The face is improved, but everything else is not. As a result, you clearly see where the face area begins and where it ends. Long hair that falls on the shoulders, is abruptly less sharp in the shoulder area, for example. Skin in the neck looks quite different from facial skin. Of course the option to improve the entire image is (at least theoretically) already available through Photoshop, Firefly and third party options like Nano Banana, but currently it often falls short because of the relatively low resolution. So what you gain by using AI, you lose again by having a too low resolution output (unless your image is fairly low res to begin with).

By the way: you mention noisy images, but you do not mention AI Denoise, which is already available in Lightroom Classic and often does a great job removing the noise from the image.