If you don't mind selfhosting, I've been developing Luna, which is a calendar webapp that can aggregate different calendar sources. For adding a new personal calendar I recommend Radicale, which you can then easily connect into Luna. Unfortunately, accessing calendars from a Google account is not yet supported, but it is absolutely something that will be added later down the line, when I tackle OAuth. Since it's self-hosted, it's fantastic for privacy and there's a big focus on security (I'm a cybersecurity researcher by trait).
I haven't really publicized this project much anywhere yet, since I'm still a few features off from being comfortable enough with releasing a 1.0.0 version, but it has gotten to the point where I personally use it every day.