ALB HTTP/3 support?

Currently, Amazon CloudFront supports HTTP/3, but Application Load Balancer (ALB) does not have HTTP/3 support based on the available information.

CloudFront fully supports HTTP/3 in all of its edge locations at no additional cost. HTTP/3 uses QUIC, a user datagram protocol-based transport protocol that improves upon TCP, TLS, and HTTP/2 capabilities. It helps eliminate head-of-line blocking, supports client-connection migration for smoother transitions between networks, and provides enhanced security with default TLS encryption.

For ALB, the current protocol support includes:

• HTTP/1.1 support by default
• HTTP/2 support when using HTTPS listeners
• End-to-end HTTP/2 support for gRPC workloads

When you configure an HTTPS listener on an ALB, it automatically supports both HTTP/2 and HTTP/1.1 on the client-facing side, negotiating the appropriate protocol with each client based on their capabilities.

There is no specific information available about when HTTP/3 support might be added to ALB or if it's in the current roadmap.
Sources
ADVPERF06-BP02 Optimize your intake request format (like HTTP/2 or HTTP/3) for faster processing  - Video Streaming Advertising Lens
Request handling and protocol optimizations - Amazon CloudFront for Media
Is it possible for alb listener to support both http2 and http1.1 ? | AWS re:Post