Would you say Github has any significant advantages over Gitlab in this regard? I always found them to be on par, with incremental advantages on either side.
Code search over all of Gitlab (even if available) wouldn't help much when many of the interesting repos might be on Github. To be truly useful, it would need to index repos across many different forges. But there's a tension in presenting that to users if you're afraid that they might exit your ecosystem to go to another forge.