Test out final copy to OSN

[jbusecke]

I would like to already future proof this for when we have the m2lines OSN pod.

In the final copy stage of the recipe I would like to just read the written store from GCS and then write/copy it to OSN.

I am not quite sure how to actually do this.

• Can fsspec handle this sort of transfer? (That would probably be the least hassle rn)
• I might have to investigate skyplane - There I am wondering how/if they support the OSN s3 interface and how to set up the authentication specifically.