But how will you setup Lightning without centralized node behind? You cannot ask every Signal user to run their own node. Cashu solve this as you can use any cashu mint to connect to a node anonymously and for thos who want, you can connect your own mint/node or a trusted friend mint/node.
Discussion
nostr:nprofile1qqsrf5h4ya83jk8u6t9jgc76h6kalz3plp9vusjpm2ygqgalqhxgp9gpr4mhxue69uhkummnw3ez6ur4vgh8wetvd3hhyer9wghxuet5qyv8wumn8ghj7enfv96x5ctx9ehx7um5wgcjucm0d5mnyh75 runs a lightning node integrated into the app; there are no excuses.
Do you use it? Because I did and it's not for any Signal user to do it, many things are hard to understand. You will get a lot of questions and frustration like: why do I "lost money" the first time I receive sats? Why I cannot get "zapped" 21 sats just for fun? What mean "my channels were closed"? Why do I have money "on chain" that cost me 30% to withdraw?
Most normies would loose all trust in it the second it cost them 10 cents for using it. Cashu solve this and many more. You can get as low as 1 sats "for fun", "to test", then slowly get more and when you want to move next step, anyone is free to transfer to any Lightning wallet or even onchain if whished andy for it.
I did use it, and my experience is the same I agree, but it's a UX issue that I think a well-funded company like Signal has a better chance of solving than Zeus. Also, even if the node is not running in the app and Signal runs it, it is way better because it cannot be rugged, although you sacrifice absolute privacy, so there are trade-offs. There is no one-size-fits-all solution; in an ideal world, we would have both Lightning and Cashu on Signal.