Ok, thanks for this, really interesting. I have to dive a little deeper to understand the mechanics / services, but doesn't look extremely complicated. I assume you use the free layer of LNPay, hence the 500 satoshi limitation.

When you said "bidirectional bridge" I was envisioning something more like what @leofinance did with their Leo / WLeo / BLeo project, in which you essentially pair Hive accounts with ETH / BSC addresses and then bridge between them.

As I understand it so far, your approach is just for this use case: the LN addresses must be linked at the origin place, in the dApp.

I am pondering what it would mean to actually pair HIVE with a BTC address (maybe in a custom_json transaction, or in the user json data) and then send over tokens from one account to the other.

I guess it would involve a relayer, something that will "wrap" tokens on both directions.