You obviously need to build a non custodial part on your wallet, a dedicated LN channel for users who want to take self custody on their funds.

Here is an example of liquidity offers you could provide for self custody: - a 2000USD channel between your node and your customer mobile node, for a price of : on-chain fees+ a 0,5%/year of the channel capa, or something like that.

Now your customers have the best of lightning with asynchronous payments even when offline and a way to self custody

"Hybrid wallets" like that (with a self custodial part like ACINQ + a custodial account for offline payments) should be the norm while waiting for better solutions for LN mobile payments...