I've been frustrated with the built-in clock and calendar on MacOS for quick access to see a monthly calendar from the menu bar. Upon searching, I've stumbled upon a couple of apps that have features I think Missive may be able to build upon. ItsyCal: https://www.mowglii.com/itsycal/ - very simple calendar icon in the menu bar, but only syncs with the built-in calendar app. Dato: https://sindresorhus.com/dato - offers a few more features than ItsyCal but for a fee. Again, only syncs with the built-in Mac Calendar App. Something like this that syncs with Missive Calendars would be a nice feature. It doesn't have to be too complicated, but offer similar convenience to these apps. Apparently you can't dismiss the default clock/calendar but Dato also suggests a way of 'hiding' it (mostly) and that works well - worth checking out.