Has anyone found a reliable way to sync calendars across different platforms?

[Ross9]

Hi everyone,
I'm curious to know what other people are using to keep calendars synced across different platforms.
At home we've ended up with a bit of a mix. I use Google Calendar for work, my personal appointments are mostly on Apple's Calendar app, and my wife is stuck with Outlook because that's what her company uses. It works fine until we try to organise something together, then suddenly everyone seems to be looking at different information.
A few weeks ago we actually missed a restaurant booking because one calendar showed an update that hadn't appeared on another device yet. Nothing dramatic, but it was annoying enough to make me start looking for a better solution.
I've tested a few things since then. Some services sync Google and Apple calendars reasonably well, but then colour categories disappear or events don't display quite the same way. I also ran into some strange time-related issues when Outlook was involved. I assumed it was a timezone setting somewhere, but even after checking everything I could think of, the problem never completely went away.
I tried Fantastical during the trial period and also experimented with manually setting up CalDAV. Both worked to some extent, but neither felt completely straightforward or maintenance-free.
Maybe I'm expecting too much, but I thought by now there would be a simple way to keep calendars in sync regardless of whether they're coming from Google, Apple, Outlook, or something else.
Has anyone here found a setup that's been reliable over the long term? I don't mind paying for a service if it genuinely works, and I'm not against a bit of tinkering either. I'd be interested to hear if syncthemcalendars.com worked for other people.