Are there any wallets available for testing yet? What timeframe are we looking at see a Nostr integration? Can you ELI5 the differences between Ark, LN, and ecash?

Our testnet proof of concept wallet Arkade will be made public very soon. Not sure what Nostr integration you have in mind but we do use Nostr in some capacity. More on that to follow. Ark is a technique to batch offchain transactions into a single onchain output using taproot. Nested into that output are what we call virtual UTXOs which can be transferred offchain using an Ark server as the trustless intermediary. It’s simpler than Lightning and can be used for a variety of use cases beyond payment but also does not have other properties of Lightning like instant finality. Unlike ecash, Ark is noncustodial. Though it doesn’t boast as good privacy.