>Electron suited us perfectly, since we could write our UI code once and make it consistent across Linux, Windows, and Mac.
This is the source of your mistake. Users don't desire to have the same UI across different OS environments, it's only an app's developers that care about that. Cross-platform UIs are inarguably a worse user experience than UIs tailored to the conventions and designs of each OS.
A Mac app that doesn't actually feel or behave like a Mac app is not a good Mac app. The same is true with tvOS apps like YouTube and Prime Video that don't actually feel or act like good tvOS apps.
This is the source of your mistake. Users don't desire to have the same UI across different OS environments, it's only an app's developers that care about that. Cross-platform UIs are inarguably a worse user experience than UIs tailored to the conventions and designs of each OS.
A Mac app that doesn't actually feel or behave like a Mac app is not a good Mac app. The same is true with tvOS apps like YouTube and Prime Video that don't actually feel or act like good tvOS apps.