Can I replace the Broadcom WiFi card with a more recent Intel one?

I'm not sure if this is possible, but it might be worth checking out this similar question. It seems like it may technically be possible, but there is not a lot of information about how to do it online, so it seems like if it is possible it would require a lot of experimentation and research. It might be easier to force install a later version of macOS on that model, like Mojave or Catalina. There is more documentation available for that kind of thing online. For example, check out this article. Good luck!