It's a Tauri 2.0 desktop app (not Electron!), so it is using the Mac's native browser view and a Rust backend. It also makes DMG size relatively small (~25mb but we can get it much smaller once we get rid of some bloat).
Right now Chorus is proxying API calls to our server, so it's free to use. We didn't add bring-your-own-api key to this version because it was a bit quicker to ship. This was kind of an experimental winter break project, so didn't think too hard about it. Likely will have to fix that (and add bring your own key? or a paid version?) as more of you use it :)
Definitely planning on adding support for local models too. Happy to answer any other questions, and any feedback is super helpful (and motivating!) for us.
UPDATE: Just added the option to bring your own API keys! It should be rolling out over the next hour or so.