Surprised not to see Livegrep [0] on the list of options. Very well-engineered technology; the codebase is clean (if a little underdocumented on the architecture side) and you should be able to index your code without much difficulty. Built with Bazel (~meh, but useful if you don't have an existing cpp toolchain all set up) and there are prebuilt containers you can run. Try that first.
By the way, there's a demo running here for the linux kernel, you can try it out and see what you think: https://livegrep.com/search/linux
EDIT: by the way, "code search" is deeply underspecified. Before trying to compare all these different options, you really would benefit from writing down all the different types of queries you think your users will want to ask, including why they want to run that query and what results they'd expect. Building/tuning search is almost as difficult a product problem as it is an engineering problem.