First: damn, I love the design of your website!

Second, that's a great list already. One addition could be the Swap In Potentiam scheme where by depositing on-chain funds into a 2-branches contract with your LSP beforehand, you can enjoy instant deployment of said funds in Lightning when you need them. The contract helps minimize trust for both parties.

Not sure it fully applies to the onramp use case, as it requires depositing funds on-chain beforehand (so that they have the time to confirm), but that's the only additional mechanism I could think of on top of the one you already covered.

Cheers!