I use a 3rd-Party Calendar widget on my Windows desktop computer: Rainlendar. It integrates with Google and many other calendar systems to allow me to not only view, but add and edit events on my desktop that then synchronize automatically with the external service to show elsewhere (other computers, tablets, phones). I desperately want to switch away from Google to Proton's calendar service, but without this kind of integration and automation, I cannot.

I also have a website that needs to, in the very least, view the free/busy state of one of my calendars for public access. At this time, I do not need the ability to write to this calendar from the website, but might in the future. I cannot find a means of integrating the Proton Calendar into my website, which is forcing me to have to stay with Google. Please add this, fix this, or provide clear instructions how to achieve this.