The well size itself is usually a function of the pixel size. A larger pixel means a larger diode that can store more electrons, and hence a larger range of light that can be measured - dynamic range.
In reality there are limits imposed by manufacturing. At the extreme, we have wafer-scale sensors used in, eg, night-time wildlife videography - https://www.imdb.com/title/tt11497922/ . Anything larger than that is typically a not-perfectly-contiguous array of smaller chips.
You can also cryocool the camera, at the expense of weight, versatility, and complexity. Most astrophotography is collected with cryocooled CCD or cryocooled CMOS sensors. This helps much more with long exposures than it does with video, but it does help.
I respectfully doubt that, development process is a combinaison of techniques that lets you do many thinks with your row data and the line between that and special effects is quite blurry (joke intended).
One way to make HDR-like with films and cheap-not-advanced material is to do a several development of the same film to the same paper, with different exposures parameters. That way you combine different ranges of the image (eg stop 1-4 + stop 4-10 + stop 10-18) to produce you final image. This is a great craft workship.
The only limit is the chemistry of the films used (giving grains at almost nano scale), multiplied by the size of the film.
Side note: development is basically a picture of a picture (usually) done with different chemicals and photographic setup.
Bit depth ≠ dynamic range.
The dynaic range is about the highest and lowest value that can be measure ("stops" are a ratio per log_2, db are a ratio per log_10):
* https://en.wikipedia.org/wiki/Dynamic_range#Human_perception
* https://en.wikipedia.org/wiki/Dynamic_range#Photography
The bits are about the gradation with-in that range. You can have 12-stop image recorded using a 10-bit, 12-bit, 14-bit, or 16-bit format.
And at least when it comes to film, it is not a linear curve, at least when you get to the darkest and lightest parts. That's why there's an old saying "expose for the shadows, develop for the highlights"
* https://www.youtube.com/watch?v=rlnt5yFArWo
Its also crucial to note at what SNR they use for their cutoff when stating their dynamic range in stops, in addition to their tone curve.
I'm only a hobbyist though, perhaps someone else can enlighten me further.
Digital is mostly limited by bits, since a 14 bit image with a linear tone curve will have at most 14 stops of info right? So we won't expect to see values pushing higher until camera manufacturers leave behind 14 bit as a standard and go higher, as in the arri cameras. They use a 16 bit sensor, and squeeze the last stop out by using a more gradual tone curve in their shadows. This means technically the shadow stops contain less information than the highlight stops, thus meaning not all stops are equal I believe (quite confusing).
[1]: "Assessing the Quality of Motion Picture Systems from Scene-to-Digital Data" in the February/March 2002 issue of the SMPTE Journal (Volume 111, No. 2, pp. 85-96).