You can search AWS account entity details in vRealize Network Insight Cloud.

Here are few sample search queries:
AWS Entities Sample Queries
AWS EC2 AWS EC2 where Security Group = '' and Account = ''
AWS interface AWS Interface where Network address like '' order by Manager
AWS Internet Gateway AWS Internet Gateway where AWS VPC = ''
AWS Route AWS Route where Account = '' group by Name
AWS Route Table AWS Route Table where AWS Subnet = ''
AWS Security Group AWS Security Group where Group Name = ''
AWS Subnet AWS Subnet where Region = '' group by Vendor ID

AWS Subnet where Availability Zone = ''

AWS VPC sum(bytes) of flows where Source AWS VPC = '' and Destination AWS VPC = ''
AWS VPC Peering Connection AWS VPC Peering Connection where Acceptor AWS VPC = ''
AWS VPN Connection AWS VPN Connection where AWS Virtual Private Gateway = ''
AWS Virtual Private Gateway AWS Virtual Private Gateway where AWS VPC = ''

All the AWS accounts in your organization that are added to the primary account are known as Linked Accounts. For more information, see Primary and Linked AWS Accounts and Add a Primary AWS Account.

Here are few sample queries for linked AWS account discovery:
AWS Entities Sample Queries
AWS Linked Account AWS Linked Account
AWS Direct Connect Gateway AWS DX Gateway where ASN = ''
AWS TGW Attachment AWS TGW Attachment where Entity Type = 'AWS TGW Attachment'