Check out Ice Cubes, another fantastic (and free!) app that supports Mac, iOS, and iPadOS today.
FYI, Ice Cubes is an iOS app. It does run on macOS by virtue of macOS supporting iOS apps, but its App Store listing notes that it's "Not verified for macOS".
There’s an API built into Mastodon to save timeline location on your account.
Ivory is planning to support it, doesn’t currently, however it does save timeline location to iCloud, readable by Ivory on your other devices.
No idea if Ice Cubes is planning to implement the native API, or if it’s currently trying to and running into issues.