You can use whatever calendar app you want, never sync it to the cloud (ie it's just a native desktop or phone app), and send ical files to share events. Hones

You can use whatever calendar app you want, never sync it to the cloud (ie it's just a native desktop or phone app), and send ical files to share events. Honestly though it's a huge pain for your recipients. Ical import isn't always straightforward. Gcal can do it but it takes several uncommon steps, for example. Much easier to just use one of the hosted web services that can generate bespoke invites for different calendar systems.