Import Matter Archive
Omnivore supports uploading the Archive.zip file generated by exporting your data from the Matter app.
To export your data from Matter, go to My Account, and choose Export data, this will send you an email with your data in a file Archive.zip. Upload that file using the uploader on this page.
More info
Note: Please note you are limited to three import uploads per a day, and the maximum file size is 10MB.