I want to be able to receive an ecashu token from someone else—one that is be minted on any standard, compliant mint—and have that token's value apply to my wallet balance. Just like every other ecash/lightning wallet (Minibits, Cashu, eNuts, etc).

If you can only redeem tokens minted by mint.coinos.io, the feature is essentially worthless because most ecash is minted by other mints. The entire point of ecash is the cross-support and interoperability of multiple, independent mints. Without that, you might as well just abandon the feature.