It seems that you do not want to understand.
If you are using Photoshop, after you have “opened” the RAW file using Adobe Camera Raw, you do not have access to the original RAW in Photoshop, since that was “converted”, usually to TIFF or PSD, but could be jpeg.
The original RAW file is never edited, with Photoshop it is always transformed by ACR to a file format that can be edited.
Photoshop doesn’t provide a compare feature but ACR does. The “before” provided by ACR is going to be the original, untreated RAW image, not the embedded jpeg.
So, your assertion that “no other RAW converter uses just the RAW file as reference” is not true.
If you really want to see the embedded jpeg version of a RAW file, you’re usually going to need to use the camera manufacturers own RAW software.
With PhotoLab, if you want to use a jpeg file as the source for a comparison, then you need to open a jpeg file for editing but, if you open a RAW file for editing, then it will be the RAW file that will be compared.
As I said before, if you “never can/would use” the RAW file, why on earth are you taking RAW images on your camera? It just doesn’t make sense.