This answerThis answer provides a good description of a task similar to what you are trying to accomplish.
This wiki page shows how scripts are serialized and deserialized. It's actually not very hard to extract the raw opcodes from the script by hand, especially if you know it's a standard type of script.
But, you may use https://chainquery.com/bitcoin-api/decodescript and paste in the raw hex of the scriptSig for a more automated solution. The parsed opcodes will be in the result.asm
field, including any raw data (such as signatures and pubkeys) separated by spaces. If you look for the element(s) of the script that start with 02/03/04, that will be the public key.