@FourOh-LLC @nicholas tech transitions always require a segmented plan and roadmap. It is a pain in the ass, but if you are tired of feeling like a soobscription milk cattle you should begin with a email mirror. Have emails that go to your on domain then duplicate to your own private server and then gmail. Or set up gmail to forward those emails.

Next you will need to implement a cross compatible scheduler so when people send appointments via gmail you can use both google calendar AND nextcloud.

Eventually, once you've ironed out all of the quirks, completely disable the mirroring and go full Nextcloud.