The Roku build is a sideloadable channel zip. Roku only accepts a signed .pkg, and the signing key can only be generated and used on a Roku device in developer mode, so the last two steps run on your own Roku: install, test, package, then upload the .pkg in your developer dashboard.
Roku renames dashboard pages now and then; each step says what the page does, which survives a rename. The key sequence and the device pages have not changed in years.
Developer mode holds one sideloaded channel at a time; installing another replaces it.
On a different Roku, or after a factory reset, restore the key with Rekey on the device's Utilities page, using a .pkg already signed with it and its password. A lost key means a new channel.
Updates: rebuild Roku in the panel, sideload the new zip, package it with the same key and upload the .pkg as a new version. Videos, streams and links come from the live feed and never need an update.