(1) Monero doesn't have transaction chaining, so if you want to "reroute a payment" you can't do it atomically. The best you can do is wait 10 blocks and then send some or all of the money to other people, and if the sender is relying on you to do that, he'd better pray you dont exit scam. Lightning is way out in front on this because it natively supports atomic transaction chaining and amount forwarding. It just works.

(2) If someone does the "wait 10 blocks" workaround mentioned above, the sender cannot see where the rerouted portion has gone unless he does some blockchain analytics, and even then, the most up-to-date techniques do not always successfully track monero payments. But they sometimes do.

Pretty much agree with Super Testnet as far as I can see (assuming you're not using custodial wallets or LSPs which changes the privacy assumptions). If you want to obscure where the senders payment went from the sender on Monero send your entire balance back to yourself a few times. At random times preferably.

It is actually more nuanced than the fueding factions usually make it out to be.

What amounts are hidden for each one and who sees them depends. Monero fees are exposed to the general public, but hides the actual transaction amount between sender/receiver from everyone else. Lightning exposes at least partial fees and amounts to limited third parties - routing nodes - but hides fees and transaction amount from the general public.

I think the best privacy, in concept, for digital cash would be hiding everything completely using a ZK scheme + offchain (to reduce exposing what little information is left). I don't think either Monero or Lightning meet that yet, but they're both constantly improving.

Some have passed the point of no return