This is for Google Sheets so I am using REGEXEXTRACT that uses the RE2 flavor of regex.

I have two cases.

Case one, two strings with a delimiter. "**String One, String Two**".
In this case I want to extract what's before the delimiter.

Case two, just one string. "**String One**".
In this case, I want to extract the whole string.

I know it's possible to test the existence of the delimiter using a google sheets formula but I wonder if there is a possibility to do that just with a regex.

Thanks!