Under Sharepoint Online, is there a limit to the size of a file that you share via One Drive? I've found references to the max storage size based on your license, but not how large a file you can share. Any insight or first hand knowledge is appreciated!
No, you should be able to share any file that is already uploaded regardless of size.
The max file size you can upload is 2GB (see limitations and boundaries), but the file size can grow on the server above the 2GB limit. Some files, like OneNote, can get large due to versioning, but the actual file size of the current version can be small allowing the clients to sync. If the current version of the file exceeds 2GB, you may run into syncing issues that prevent you from uploading changes to the document.