You’d have to open a lot more windows and text editors to accomplish what cosmic-tweaks does, I’d argue that’s more annoying than simply opening an app and toggling a setting.
The hope is that these setting one day will make its way to the official settings apps, in the meantime, we got cosmic-tweaks.
None of these settings are available in cosmic-settings yet, if one day there's a need for them, we could port this implementation to the settings app and remove them from cosmic-tweaks.
I made this to experiment with COSMIC without having to change config files manually, after realizing this could be useful to other people I decided to announce it, but it’s designed for tinkerers, you don’t “need” this to have a good experience with COSMIC.
I have wished this for years now, the most seamless experience I’ve gotten from Apple Music is picking where to play music from my Apple Watch, but this is not the same as what you’re saying, it does not transition your currently playing song to other devices, just lets you control playback on other devices.
Notepad did what it needed to do, but it could be improved in a lot of ways