I got my mother an iphone thinking iOS would be more easier for her to use than Android, as she is not much into technology stuff. And it kind of is, though it'

I got my mother an iphone thinking iOS would be more easier for her to use than Android, as she is not much into technology stuff. And it kind of is, though it's easy to hit the walled garden. And I wanted to create a common calendar so one can set reminders for her (and all of us) about medical appointments, medicines and stuff that we all could manage from our phones, wheter Apple or Android, or my computer, via a web browser, caldav or whatever. I imagined that would be second nature, after all it's just a calendar, right? Well, it's 2023 and you can't do that because reasons.