I hope I've understood your question right. To find similarity score you can use difflib
built-in module:
from difflib import SequenceMatcher
def similar(a, b):
return SequenceMatcher(None, a, b).ratio()
for s1 in df['A header']:
df[s1] = [similar(s1, s2) for s2 in df['A header']]
print(df)
Prints:
A header schwabstsoct2022 schwabsts schwabregionaloct2022 schwabregional2 flagstar-2022 flagstar-2021
0 schwabstsoct2022 1.000000 0.720000 0.702703 0.516129 0.482759 0.413793
1 schwabsts 0.720000 1.000000 0.466667 0.500000 0.272727 0.272727
2 schwabregionaloct2022 0.702703 0.466667 1.000000 0.833333 0.352941 0.294118
3 schwabregional2 0.516129 0.500000 0.833333 1.000000 0.142857 0.142857
4 flagstar-2022 0.482759 0.272727 0.411765 0.285714 1.000000 0.923077
5 flagstar-2021 0.413793 0.272727 0.352941 0.285714 0.923077 1.000000