I recommend

I recommend this calendar management, different from what you usually find, the self-hosted solution being a very good idea in my opinion.

The extension does what it says and offers enough configuration possibilities to satisfy most people.

The mobile application has not been updated for a while now, although a refresh and some new features would be very useful and especially normal nowadays.

The support of the paid solution is very competent and responds quite quickly (12 to 24 hours in my case for the first contact), but the main thing is that they do the job.