I'm working on Spilman (i.e. one-way) channels over Cashu, it's been my main focus since around September
A client and a service provider do need to trust the Cashu mint, but they don't need to trust...
PS: Cashu is obviously good with Bitcoin and Lightning, but the Cashu protocol with with any currency ('unit' in Cashu lingo), so this channel system can work with any stablecoin if there is a Cashu mint that supports that coin