cashu ecash is a custodial iou for sats on the ln node of the mint but the tokens are bearer assets on the device it offers superior privacy over any other custodial LN solution the "ecash" will typically be denominated as sats but can also be in usd the mint can't rug an individual but could rug the whole mint if users are on the same mint tokens can be sent out of band by dm, text, email for free Minibits pays any ln invoice as well there are certainly ways to zap self custodially but minibits has amazing product fit for nostr send out your balance to redeem sats into self custodial ln channel on Zeus for example