I'm pretty tech savvy and experimented with a bunch of solutions and by far the most straightforward and privacy respecting way to sync calendars and contacts between Android and MacOS that I have found is to use Nextcloud. Create a free account here, you can select which provider from the drop-down menu, I had a look at them all and chose Wolkli as their servers are located in Switzerland and the free tier has encryption enabled by default. You then use DavX5 on Android to sync contacts and calendars to Nextcloud, and then in a browser on your Mac go to settings in your Nextcloud account and download profiles for MacOS/iOS to sync them to the default contact and calendar apps.
The solution mentioned in the comment above using Radical Will work syncing with the calendar in Thunderbird (which just got a redesign) but not the default calendar app. NextCloud will let you use the default contacts and calendar app.
Notes I do sync offline using syncthing and obsidian.