How to extract specific keywords within the frame and extract only that data with in the separators

You can construct a regex pattern using the given keywords then use Series.str.findall to find all occurrences of regex in series:

import re

keywords = ['enst.35','enst.18','enst.98','enst.63']
pattern = '|'.join([rf'[^,]+{re.escape(k)}[^,]+'for k in keywords])
result = df['col'].str.findall(pattern).str.get(0)

#print(result)

0    abc|framex|gtk4|enst.35|pxc|h5g|
1     abc|frbx|hgk4|enst.18|pif|homg|
2        abc|frame|gtk|enst.98|pc|hg|
3                                 NaN
Name: col, dtype: object

You can test the regex pattern here

You can try in bashscript as follows:

for STRING in enst.35 enst.18 enst.98 enst.63; do
  tr \, \\n < file.txt | grep "$STRING" || echo NA
done

With str.extract and str.split(',) to take the last comma separated value:

df['Data2'] = df['Data'].str.extract('(^.*enst.35\|.+?\|.+?\||^.*enst.18\|.+?\|.+?\||^.*enst.98\|.+?\|.+?\||^.*enst.63\|.+?\|.+?\||)', expand=False).str.split(',').str[-1]

You could create a list of keywords and do list comprehension as well per another answer.