chrome.storage.sync limits vs. Google Keep

Question

I understand the limitations of QUOTA_BYTES_PER_ITEM and QUOTA_BYTES when using chrome.storage.sync. I'm finding them quite limiting for a annotated history related extension I am writing. I understand that local storage could avoid this problem, but I need a user to be able to maintain their data as they move to other devices or someday replace their machine. My question is - are their other storage methods to get around this? What about Google Keep? It is an extension, but it appears capable of a "unlimited" storage of notes, or at least far more than the limitations of chrome.storage.sync. Is it simply not playing by the same rules, or are there other methods I could be using? Currently I'm concatenating information into large strings in javascript and storing these using chrome.storage.sync. Then parsing that information later as my database. Thanks for any help!