[pahool]

The "Handy Library" Android app includes an ISBN scanner and allows you to import and export collection data.

You could also check out some of the tooling and APIs around openlibrary.org. Unfortunately, I think it's basically a moribund project, but may have sufficient tools for your needs. I know they have a list feature, but I don't think ingestion is particularly easy; nor am I sure of the import/export functionality around their lists.

edit: I'd forgotten about librarything (mentioned in another comment). They have better tooling that openlibrary.