Hi guys,
ID Util does run under Catalina (macOS 10.15) and does work with InDesign CC 2020 (I think it’s going by InDesign 2020 now) documents. But, as David mentioned, ID Util is being phased out and replaced by IDMarkz (https://markzware.com/products/idmarkz/).
IDMarkz does offer free features in the Freebie (https://markzware.com/products/idmarkz/download/), among which are the same Quick Look previews offered in ID Util that you’re looking for. Just like with ID Util, IDMarkz can be used for free to preview documents. Converting to IDML is the main feature that would require a paid license.
I hope that helps clarify the issue a bit.