I've yet to study more about sidechains such as Liquid, so I can't say whether those off-chain solutions are trustless, but I'm relatively confident they are; otherwise nobody would use them.
You definitely need to trust the federation that controls peg-outs [1]. From the whitepaper [2]:
[...]
I see.. There's some decentralization happening at least, but for me it's not comfortable using a system that requires trust. At least not as the only way to use BTC.
It's possible to have a light wallet to use for small purchases that relies on such a system, but I'd agree that nobody should put majority of their wealth into such a trust-based sidechain.
But again, to highlight: this doesn't exist in Lightning. Such type of trust doesn't exist, you just have to take care of your node by yourself and not fuck things up (like restoring an outdated backup or not have backups..).