restoring pixelated photos using AI

There is something about the way this question is usually asked, that misses what is actually asked for: This is not "restoring" something already present. It's not a question of "uncovering" information. This is upsampling, pure and simple, inventing information that isn't there. Pulling pixels out of a hat, so to speak.

What AI can bring to the table, is compare to other images it already "knows" from what the algorithm has been trained on. So this usually works well on common textures like hair, fur, textiles, grass, foliage and so on. It will usually also work well on blurry text.

It will not be as successful on unique unpredictable detail. It can't "restore", only rebuild.

We all want this feature. The technology is getting there. There are some neural filters that work OK. 

Have you tried the Super Zoom Neural filter?

https://helpx.adobe.com/photoshop/using/neural-filters.html

https://helpx.adobe.com/photoshop/using/neural-filters-list-and-faq.html