Various team calendars: Google, Synology and Nextcloud

I have Nextcloud running as a turnkey LXC container on Proxmox. I have my own domain and leads to Nextcloud. The domain is listed as a trusted site and I can access it from outside.
My family uses Nextcloud Calendar for their appointments. At work we use a Synology NAS and there the calendars that we share. In my sports team we use a shared Google calendar, which I help maintain.
It would be important for me to be able to at least see all calendars in one of the web clients and ideally also be able to edit all calendars. It works well on mobile. I have all calendars in my app under Android via DavX, I can edit all of them and they are also syncronized. I would like to have this on the PC without an additional client. Preferably in Synology and Nextcloud WebClient at the same time. If I understand correctly, I get the Google calendar editable imported into my Nextcloud. I failed at Synology. Can only import it without sync. Is there a way to synchronize the two CalDav calendars on different servers in both directions?

That’s not possible, no. The Nextcloud Calendar app only provides read-only subscriptions, it’s not a full calendar client for external sources.

and is there a good windows client where i can integrate more thean one caldav servers and google? maybe one not includet in an email program. dont like thunderbird and outlook calender.

I don’t know anything else than those two, sorry.

Well, in my experience it does the job.

Do you have any particular reasons for avoiding it?