I was subscribed to paid g suite for more than 2 years and only used custom domain email. When Apple released iCloud+ [0] or whatever it is called, I immediately migrated there and am really happy with it.

You will probably need to subscribe to some iCloud plan and have an apple device. But if you already use those, you are good to go.

[0] https://support.apple.com/en-us/HT212514