Smartphones are fine. There are no problems today with finding good calendar software for any smartphone out there. But when it comes to desktops (or laptops), there are exactly two cases in which using calendars in 2024 isn't a complete disaster:
I really don’t see the issue. If the work account uses Google or Microsoft I use their respective web apps and export an ICS link to see the blocked slots in my own personal calendar.
For my own personal calendar I use CalDAV, which is widely supported, and an app that can import ICS links. (Self-hosted Radicale server and the Calengoo app for mobile and desktop, for the curious.)
I really don’t see the issue. If the work account uses Google or Microsoft I use their respective web apps and export an ICS link to see the blocked slots in my own personal calendar.
For my own personal calendar I use CalDAV, which is widely supported, and an app that can import ICS links. (Self-hosted Radicale server and the Calengoo app for mobile and desktop, for the curious.)