Currently, iCloud sync does not encrypt data end-to-end (E2E). This is a loss of privacy, compared to what Safari [1] and Firefox [2] offer by default, and what Chrome [3] offers through a manual setting. It means that a compromised iCloud account will reveal private details of tabs, bookmarks, and perhaps one day browsing history that is synced. It may be possible to use iCloud encrypted values [4] to achieve E2E to reduce development time. As a Safari and Firefox user, this is a requirement for me before switching to Orion as the default browser. Thanks for the work on this excellent project, and I'll be watching to see how this evolves.
[1] https://support.apple.com/en-us/HT202303
[2] https://hacks.mozilla.org/2018/11/firefox-sync-privacy/
[3] https://support.google.com/chrome/answer/165139
[4] https://developer.apple.com/documentation/cloudkit/encrypting_user_data