channel default sets, and it applies when a message goes to you.
channel list shows the channels you connected and which one is your default. Linked channels live on the server. channel default is a preference on this computer for messages to you.
--via on inbox send is a one-time delivery override. A reply has no --via: it stays on the conversation’s channel.
Voice, iMessage, WhatsApp, webhooks, and a custom email domain are not setup guides yet. See Coming next.