Looking For An ONVIF Camera That Can Run Inside Of A Refrigerator.

David, do you mean inside of a commercial walk-in cooler or case, or a consumer-style refrigerator?

On the outside chance that you mean the appliance variety, possibly in a commercial setting, i.e., lunch/break room, I'll mention one of the few true end-to-end solutions for this vertical.

The IP addressable Samsung Smart Home Refregerator with 3 built-in Samsung cameras. Comes with client app for remote access. Put an end to that bothersome food theif in the break room! ;)

See:

IP Camera For Freezer (0 Degrees Temp)

I have a March Networks Nano Dome installed in a commercial freezer for over two years without issue.

There are plenty of cameras rated for temperatures down to -40c. Where the problem of fogging usually occurs is when the camera is located near a door and the temperature changes rapidly when opened.

Will this be near the door?

Commercial walk in refrigeration units are usually kept between 34F and 40F. Most cameras that are outdoor rated should have no problems with those temps. To be more sure, stick with a sealed unit, like a bullet or turret style. I would also make sure you have a sealed back box to keep moisture away from the connectors.

If you need something capable of freezer temps, as in below 0F, your list may be shorter, but shouldn't be too hard finding some choices.

Here is a good example:

Hikvision DS-2CD2342FWD-I WDR IP Turret Camera

Temp Range: -30 °C ~ 60 °C (-22 °F ~ 140 °F), Humidity 95% or less (non-condensing)

That range should work in just about any freezer or refrigerator. It also has WDR to help with varying light conditions. It also has IR for when the lights are off.