I need to look at the phoenix charging again it seems. I thought that they charged for the initial channel setup but that the fees once setup were pretty reasonable (standard LN fees).

The problem with using liquid is both the sender & receiver need to have liquid wallets. It wouldn't be an issue if liquid became more popular, but it would then shift the issue to the amount of trust placed in a single federation.

I like the fedi model of many smaller federations (dispersing the risk) with federated LSPs handling external payments. Invoices are still paid in lightning but it reduces the number of lightning nodes required within the network with more acceptable centralisation.

Custodial wallets have become more prevalent because of nostr & LNURL (no bolt 12 still). I don't love it but I'm reminded of how new the lightning network is. I'll use whatever tool suits my needs, including Liquid if it makes sense to.