Make it seamless for people to migrate. Duplicate comments/posts/vote API calls to Lemmy. Then they could just drop the Reddit side whenever they want, and users wouldn’t have to do any work. Most wouldn’t even notice the change.
Of course they’d have to keep the app up in the meantime, but I’d donate to that fund.
Christian already commented on this. He said it’s a lot more work than it might seem, and he’s not interested in maintaining that. And I don’t blame him, the poor dude needs a break from technology for a while.
In the Android world, the Sync for Reddit developer expressed some subtle interest in Lemmy, but has not committed to anything one way or the other.
I think the big push to converting Reddit apps to Lemmy apps won’t happen until July. We’ll have to see.
I wonder if he’s yet aware of this: https://github.com/derivator/tafkars/tree/main/tafkars-lemmy
Tafkars is nowhere near ready yet. It barely support read-only viewing at the moment.
There are some pretty annoying problems to beat (notably the way pagination works, which Reddit does a lot better than Lemmy in my opinion). The Lemmy API also doesn’t provide certain details the Reddit API supports (i.e. media size) and API documentation in general is quite scarce.
It would probably be easier to rip out the Reddit API entirely and build a different client for Lemmy than to jump through the conversion hoops.