Hi @Caffeine11,
You can save the outputs of the API calls by copying and pasting into a generic notepad app, saving it as a .json file, then once its saved, you can use Excel tools to parse the .json file into a workable spreadsheet. Check out this how to guide from Microsoft: https://learn.microsoft.com/en-us/power-query/connectors/json.
Groups are an interesting question, they are found under the “Audiences” service in the drop down. To get all the groups, you can look at the call “Get All Audiences”, but remember its only going to show you so many results, so you’ll need to sort by page if you have lots.
For Reports, I’d check out the “Analytics” service from the drop down, then the “Report”, then “Get New Reports Available in the Platform”. That should provide the list, but the same pagination might also apply here.
The .json trick I mentioned above will also work for the responses you get from these calls too!
Good luck on the API journey!