2023 big year for Fuji?

I'd have to respectfully disagree here. Comparing film ISO to digital ISO is fine. However talking about sensor signal to noise ratio and then Gain as if they don't interact is a bit of a problem in looking at how sensors function and how they readout to generate the RAW data.

You are essentially correct in everything said seperately but the system doesn't work in the dicrete way you imply. That the amount of light a photo site captures on a sensor is set for the sensor is correct. However the sensitivity of the photosite is defined by the very amplification circuits you mention. That is the response to the signal from the sensor can be increased or decreased as a function of the gain in the readout circuit. The way you put it it's like the flow is: -

Light --> Sensor --> RAW --> Signal Gain --> Image processing? Its really like so: -

Light --> Sensor (with Gain/Amp applied (as pretend ISO) ) --> Image Processing --> RAW Output 
If signal is too high in bright light it'll max out the sensor readout and information is lost if it's too low it'll bottom out sensor readout of the signal and again information is lost (because the sensor is not a 0-whatever volt signal it floats say as a 1-5v signal (example only)). When increasing gain or reducing it too much, more noise is introduced. Signal to noise Ratio increases in either case (Overly large signal or overly small signal both create more noise) . You can't really de-couple the amplification of the sensor signal from the sensor sensitivity/snr the of the signal from sensor to the image processor. RAW output is a function of both aspects of the system.

In essence ISO on film and ISO on digital sensors have the same effect less/more noise and less/more sensitivity the only significant difference to me is you can change ISO without changing film.

For reference (and not a flex!) I come at this topic as an engineer of many years who spent 14 of those years using CCD and CMOS sensors on Robots to look at things in 3D and get them to act accordingly so my thoughts are not random I've gone quite deep on programming these things and knowing how they work and how they 'see'.

Other information that may be of use or interest is sensors generally perform multiple readouts into multiple matched amplifiers. The signals are in pairs and one is inverted. The 1st is then added to the 2nd signal to try to establish a noise signal (a + -a). If you add a to -a you should get only noise. You can then remove this from the original signal in a kind of feedback loop.

Problem is that inherent noise in the system will only grow as gain goes too high or too low (Like high or low ISO does (with digital cameras) and high film ISO does with Film) so noise will become an increasing problem as you magnify this issue by ramping up gain. Also the less the strength of the original signal the more of that signal is noise (of a more significant kind) so the signals are harder to discern from noise and clean-up hence noise at low light is way more an issue. You can even notice high ISO at higher light levels has less noise as it's still a decent signal (except where it maxes out).

By maxing out a signal I mean in the digital sense. In simple terms if the readout of the digital sensor can only report 0 as black and 255 as white and you up the gain too much so everything is 255 (Gross overexposure from) all your information is lost from an image point of view. Dropping ISO (gain of sensor readout) might recover that so the sensor output can represent light and dark again properly. Obviously Shutter Speed and Aperture also play a central role in that but that goes without saying.

D