Context: - Shot RAW+JPG - Import Raw+JPG - Lightroom Settings: DO NOT "Treat JPEG files next to raw files as separate photos"! --> In this configuration, JPEGs are treated as invisible/unaccessible ‘sidecar’ files. The default Lightroom rendering off RAW files may be quite different from the JPEG files coming from the camera. Currently, with this configuration, if you want to have a look at the camera's JPEGs, you can not do this within Lightroom, you need to use a different program!
Feature request: Showing the JPG in Lightroom should be possible. Library module: Loupe view, Compare view, (ev Grid view), ... and Develop module: "Before and After" view --> Possibility to show JPEG in the "Before" part of this view. (Where "Showing" means rendering, not displaying 2 thumbnails.) Mixed mode: I suggest to show (render) JPEGs if no developper settings are present, and Lightroom RAW rendering for photos with developper settings.