I would love to do: - set aperture priority (fully open for most cases) - set shutter speed to AUTO with a limit (never open for longer than 1/100 s) - set ISO to AUTO with a limit (never go above 6400)

If there is insufficient light, then by all means, the camera should adjust the shutter speed past the limit, but not until it has used all the available "reasonable" ISO range.

It's a shame I have to wrestle my Sony a6400 to get something even remotely close to this.