Is it possible, with the new analytics API, to get analytics (for example, App Sessions) for a specific date, such as 2 months ago?
The Analylitics Report APIs does not allow you to query data based on specific report type and specific date range.
You can create ONE_TIME_SNAPSHOT
data access request.
Apple will prepare a set of reports that will contain all the data.
Once they are ready you can select only the report instance of the report type you want.
To select the target dates, you will need to download the report file or files and filter by "Date" field within the files.