Are there any signature algorithms with pseudorandom signatures?
A valid signature $\sigma$ satisfies the very special property that $\textsf{Ver}(vk,m,\sigma)=1$, whereas a random value $\tilde \sigma$ will surely not satisfy this property. So a signature simply cannot be indistinguishable from random if $vk$ and $m$ are known. And if you consider $vk$ or $m$ to be secret, then you are leaving the standard realm of signatures. The paper mentioned above by Maeher does exactly this.