The recent rewrite of github search has probably made sourcegraph irrelevant. If you may recall, original github search used almost the most horrible algorithm possible. It dropped all punctuation and spacing and just searched for identifiers. No patterns allowed, no quoting allowed. One of the only meta-arguments was filename:xyz.
Now that github has improved its basic search functionality, sourcegraph might be doomed.
I used sourcegraph at Lyft which (at the time) had unlimited money to waste on software tools, and installed the open-source version at Databricks but nobody cared.