Are there any non-custodial LN wallets that automatically onboard everything to LN? I guess onchain invoices would have to be a channel open or some sort of swap...?

If someone doesn't have a node, they have to use Wallet of Satoshi (which is fine) to move money onto LN & then they can send it to Muun or elsewhere without complications. But if they go directly to Muun (skipping Wallet of Satoshi) every attempt to pay a LN invoice seems to involve opening a channel & paying onchain fees. That's a really bad UX because even as someone who knows what's going on, Muun doesn't show me how much of my Bitcoin is available on LN vs onchain.