There's an open standard, icalendar (https://icalendar.org/) which represents calendar entries. Invitations you get in the mail come this format too. The easiest way for your map, address book, reminders etc to integrate is just to talk to your calendar server. The apps need not know about each other at all.
Google and microsoft of course may do some non-standard futzing around within their proprietary stacks: you can often see these problems when you try to connect to something outside their silos, though in my experience the standards integration in google calendaring is pretty good (especially when compared to their mail system). It's been a few years since I had to interface with Exchange calendaring but back then it...wasn't good.
So in any case there's no reason you couldn't write a small service that spoke ical over the network and this plain text calendar's format locally. Then it would appear normally in your partner's iphone, handle your kids' schools' calendars etc.
Whether it would be worth doing that is literally an exercise for the reader...but you'd get the same level of integration as you would with, say, Apple's icloud calendar services.
This is one of those situations were worse is better.
> Google and microsoft of course may do some non-standard futzing around within their proprietary stacks: you can often see these problems when you try to connect to something outside their silos, though in my experience the standards integration in google calendaring is pretty good (especially when compared to their mail system).
Yes, crossing the two is often still a hot mess.
The first paragraph sounds great in theory. The second paragraph sounds more like what happens in practice...
Sadly, in this particular case, I can forgive them. The fact that iCalendar is the best we have is sad. There is a lot of room for improvement.
https://kristiandupont.medium.com/the-sad-state-of-webcal-d8...
I've been looking for something like this that will let me edit in plaintext but also sync both ways with gCal for the benefits of plaintext but also the caveats that you mentioned.
Any time slot that matters to me goes into a proper calendar so my time is marked as blocked and people know that I'm busy and don't dump meetings in it. I literally block time to code. Likewise, a lot of my work is coordinating work with others and we use Asana and Github issues for that sort of thing. Other tools are available. But the key feature usually is that you can use them with a team and assign stuff to each other, edit them concurrently, and have some non technical team members doing so as well.
Doing csv exports and imports is feasible for calendars and issue trackers but it doesn't solve a problem I have (except when migrating to different tools). As data input tool that seems not really great. It's actually why I like Asana; I can just type an issue, hit enter, type another one, etc. It feels like a spread sheet tool.
That said, this kind of text format is useful if one needs to keep track of calendar information for a specific project (in a project folder).
My Google cal emails me notifications, works with desktop calendar apps, integrates with Maps, etc. It autofills addresses, adjusts for time zones, syncs across my 4000 devices, allows me to edits dates via text input or GUI/drag 'n drop, etc. (Not shilling, Apple cal is probably similar.)
Even my todo list went from org mode to Google Tasks because of the integrations with Android, Google Calendar, etc.