How to get all the savesets of an individual manua Oracle RMAN backup ?

You can start by using mminfo to list the savesets that are contained in the volume where the RMAN backups go to

You might be able to use the mminfo command's options to get only the info you need, or, you could use a spreadsheet program to filter out the results from the list of savesets you get from running the mminfo command to finally arrive at a list of only RMAN backups' savesets