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.
"Other contacts", which are automatically added when you send an email to an address previously unknown.
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 "Delegated contacts" (meaning "shared with you")(Feature request: https://missive.canny.io/feature-requests/p/sync-delegated-contacts-from-google).