The "Import / sync contacts from Google" (https://missive.canny.io/feature-requests/p/import-sync-contacts-from-google) feature is great, but it only syncs your own contacts.
Contacts delegated to (meaning "shared with") you are not included. With use this feature in Google Workspaces quiet a lot to provide each other with up to date and complete contact information.
They should be (optionally) included in the contact sync. Maybe in a separate Missive address book that is read-only.
The same is true for "Other contacts", which are automatically added when you send an email to an address previously unknown (Feature request: https://missive.canny.io/feature-requests/p/sync-other-contacts-from-google).