After poking around a bit, I did discover that if you already have some kind 30002 relay sets created, Jumble can import them. When you are on the screen for editing your relay sets in Jumble, you just have to select "Pull from relays" at the top right, and it will show you the relay sets you have saved.

One would expect that the "Push to relays" option would do the opposite, taking a relay set you have in Jumble and saving it as a kind 30002 relay set, but it doesn't appear to do that. At least, it was not available when I selected "Pull from relays" after Jumble had confirmed the set was pushed to my relays. Perhaps nostr:npub1syjmjy0dp62dhccq3g97fr87tngvpvzey08llyt6ul58m2zqpzps9wf6wl can shed some light on how that works.

Creating relay sets in Jumble on one device that can easily be imported on another would be very helpful. For now it seems you have to create the kind 30002 set in something like listr.lol first, and then you can import it into Jumble on any device.