There isn’t a way to display two sources at once. All Lightroom Classic views are based on the same currently selected folder or collection. InDesign won’t help much with this because, as a page layout application, it only displays content you added to a page. Although I suppose you could create a page with a grid of empty graphics frames on it and drop an image into each frame, but that would not be easy to rearrange or sort by time.
If you want to stick with Lightroom Classic, one idea is to sync the target collection to Lightroom Photos in the cloud, which would let you view it in Lightroom in a web browser, phone, or tablet while you keep the Grid view in Lightroom Classic set to the source collection.
Adobe Bridge is certainly another option, because it is possible to open multiple Content tabs that are set to different sources. Bridge can browse the same folders as Lightroom Classic. I just tested it, and Bridge can have two Content tabs viewing different folders or collections. However, although Bridge and Lightroom Classic both offer collections, their collections are not compatible with each other.