that sounded pretty much like they are using LN 🤷🏻‍♂️:

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Initially conceived as an alternative to the Lightning Network, Argentieri emphasizes that his company’s immediate focus is on supporting the adoption of Bitcoin's popular Layer 2 solution.

"Lightning has made tremendous strides recently,” he said. We believe we can leverage this network effect to bring Ark to market and enhance the self-custodial experience for existing Lightning users."

Ark addresses these challenges by utilizing trustless servers, allowing Lightning users to mitigate the difficulties typically encountered with operating Lightning infrastructure. A recent trend in reducing the costs of on-chain operations related to liquidity management has been to rely on custodial or federated options such as the Liquid sidechain.

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...anyway. I'll wait for more clarifications.