Find ISBNs for a list of book titles

Not a question about using LibraryThing, but maybe someone can help me.

Over the years I have kept a database of my wishlist, but for each book I have entered only author and title, not ISBN (I didn't find it useful at the time).
If I'm not mistaken, this database at the moment is useless for the LibraryThing import feature, because it needs ISBNs to work.

Before I embark on the boring task of finding the ISBNs for all these books and manually adding them to the file, I wanted to ask if there exists some site/tool on the web where you upload a csv file with author & title and you get a "probable" (I'm not demanding 100% accuracy here) ISBN for that book. That would speed things up for me.

I've looked a bit and found this https://isbndb.com/ or https://pypi.org/project/isbntools/ but honestly I don't understand what I'm supposed to do with them.

Most of the books in my file are in Italian so, if such a site/tool/service exists, ideally it would have to extract data from international sources.

Maybe there is no solution and I'll have to do everything manually, but I thought to ask first.

Thanks

I don't believe that is correct. ISBNs are not required for book imports. There's a particular format that the book data needs to be in but I've never used it so I don't know the details

ISBNs are only needed if you want LT to use sources.

Oh
So if I use my file as it is it will add the records with this bare minimum info (title and author)? It might work for me.
I didn't know that

Your file has to match the sample file.

Your file needs to have the exact columns in the exact order of the sample, but all other than title are allowed to be blank.