Compare Regex input and Excel spreadsheet and print/highlight the difference

So I am trying to create a program to do the following:

1. Allow a user to manually input some alphanumeric characters, with some regex included - e.g. ^MASDJOEUFJ0.|^WAOIFUWH2IW9.|^abcd130.
2. Remove all regex characters/delimiters - ,.|^
3. Print out the new alphanumeric string - e.g. MASDJOEUFJ0 WAOIFUWH2IW9 abcd130
4. Load the contents of an Excel spreadsheet into memory, for comparison purposes
5. Compare the alphanumeric string (in step 3) against the contents of the Excel spreadsheet
6. Print/highlight only the differences

I am new to Python but using my previous programming experience I have created a program which will do up to step 4 but I am having issues trying to work out the last 2 steps - here is what I've done so far:

import re
import pandas as pd



str = input("Enter Regex : ")

pattern = r"['^\', '\\.|']"

str = re.sub(pattern, " ", str)

#str = str.split()

print (str, "\n", "\n")



df = pd.read_excel (r"C:\Users\...\...\...\Spreadsheet_Comparison.xlsx")

#print (df, "\n", "\n")

I am not sure if I have even used the correct approach so far or not, so any help/guidance here is appreciated.

I am aware that this might not be the most professional way of writing this program but I don't need it to be, I just need something basic that will do the job, and that is easy and straightforward to follow.

Thanks in advance for all the help.