Is there another app that could feed the data to citrine already now?
Discussion
If you can get a jsonl file from a relay you can import it.
Nostrudel can use citrine as a cache relay and it sends everything it fetches to citrine.
I made i pull request for nostrsync a while back to add support for exporting your data as jsonl but i think the owner is busy and didnt review it yet.
You can get a jsonl file using nak in your computer for now
I think with nak you can also fetch from a relay and send to another. Just need to change amber to 0.0.0.0 first and get the ip address from your phone.
Never tried this before
You may be able to add an up stream from strfry.