What input profile for color management is best?

As a newbie trying to learn digital photo editing I’ve done a bit of investigating about setting the “Input Profile" for Color Management and remain puzzled. This includes reading the related RawPedia material.

While “Camera Standard” sounds like a good choice, the description of this option doesn’t provide any certainty about what is ultimately going to be selected for use and further suggests that there are many possibilities. While this might be fine for someone who doesn’t much care as long as the result is sufficiently pleasing for someone trying to learn cause and affect it is not comforting.

Another choice is “Custom” which implies that you should know what you’re doing before selecting this. My camera is a Canon but apparently not one of the models that enables the DCP selections. Insofar as my camera is a fairly inexpensive entry level model this is not surprising. However, I do have the Canon software installed on my computer and have found a couple of files that appear to be ICC profiles. One of these uses the suffix .icm whereas the other one uses .icc. What is the difference? I’ve confirmed that they both appear to function properly when used as “Custom” Input Profiles. AFAIK, this software is not specific to my camera but is what Canon supplies for use with all of their cameras. Therefore, I’m thinking that these profiles must be a bit generic and do not do anything particular to a specific camera model. Is it possible that all Canon cameras are enough alike in this respect that model specific profiles would not be relevant?

An experiment involves the use of “Camera Standard” which as best I can tell is the default along with one of the “Custom” Canon supplied ICC profiles on the same raw image with everything else being left unchanged. There is quite a bit of difference in the appearance of the resulting images. Links to jpeg images derived from the experiment are as follows:

https://photos.app.goo.gl/CmvluQOq336Ln7TX2 : Camera Standard
https://photos.app.goo.gl/405cM3ThAijig4Sg1 : Custom

My interest is in establishing a starting point for editing raw files where I get to see the rawest (least altered) image possible no matter how bad it might look. However, it does seem that matching the color space that is appropriate for the camera is desirable. Is there good reason to choose one of the above options? Is it possible that neither is a good choice?

Use the default option - it’s default for a reason.

Generally speaking, the vertically-lower the input profile option, the better.

None.

Third-party profiles may or may not work well.