No, I'm afraid not. The reason is that neither could be made use of in the default image really, and so they'd be used by a small minority.
Both GPG and SSL support are really big (in space) and slow (execution speed - remember, we support 486). Increasing the base image size by say 50%, and boot time by 5x, they aren't tradeoffs worth it. Checking signatures only at download time would expose you to anyone who has had physical access to your usb stick, etc, and so isn't really a complete solution.
An option I thought about was writing a small public key signing program, and I created one using the ed25519 elliptic curves. The binary was about 75kb IIRC, which would be acceptable in the base image. However, the speed is still prohibitive for low-end computers, and a home-grown solution would be scoffed at by the general public, even if it was using a verified library for the cryptography.