NAT Gateways provide secure outbound internet access for instances in private subnets, but they have limitations such as cost, single-AZ dependency, lack of inbound connectivity, potential port exhaustion, and limited traffic inspection capabilities. These limitations can be mitigated using multiple NAT Gateways across AZs, VPC Endpoints, IPv6 with Egress-Only Internet Gateways, and monitoring tools like VPC Flow Logs and AWS Network Firewall.