Accept google calendar invite with iCloud calendar

I use an iCloud calendar account for my private life, via the macOS and iOS Calendar apps, and Fantastical. Whenever I get an invite from a friend using Google Calendar, I get an email with an invite.ics attachment. I can open the attachment using calendar to import it, but this will not notify the sender that I have accepted the invitation. I have a gmail account and can accept the invite in Google Calendar, but then it is in a separate calendar from all my other events. Is there any way to really accept an invitation sent from Google Calendar that allows me to have the event in my iCloud calendar? The reason is that I have shared my iCloud calendar with my partner (read-only), so they can see what I'm up to and plan accordingly – so simply showing my Google Calendar in Calendar.app doesn't work for me.