Yes, it is not just hard drives that need to be wiped. Network routers also contain storage with even more valuable information, especially when it relates to accessing that network, or other 3rd party networks. Even remote access information around VPNs is stored on routers.
Although the report focusses more on corporate networks, the same really applies to home networks.
You want to at least apply factory settings to your router before discarding it.
See https://www.welivesecurity.com/wp-content/uploads/2023/04/used_routers_corporate_secrets.pdf