Filter by Inactive to see all those members who have never interacted in the community. You can choose to send them activation DMs or event setup automation to send a series of targeted messages.

For folks who are inactive in the community, you can increase the chance of engagement by sending them emails instead of DMs. But this is only possible for Slack and Discourse communities where you get the email IDs of members.

After you apply the filter, export the CSV and gather all the emails into a mailing list. You can then send them updates about the community to nudge engagement.