doesn't it use up a lot of disk space compared to other distros because of the way everything is set up?

Yep disk space and learning curve are the two major downsides to Nix. The former has never been a problem for me in practice, just run garbage collection once a month. The latter was a big problem, but is now mitigated for most people by LLMs.

Yes. But disk space isn't exactly the most valuable resource you have as a developer/power user

Yes, however the space is not „used up” in a classic sense. It’s a cache, so you can give up some of it and reclaim your space. Fresh after a full cleanup it won’t take much more than a regular distro.

actually once I garbage collect, nixos actually uses up less disk space for me than other distros

Use nix.optimise.automatic = true in the config and perform nix-collect-garbage if necessary. With this it doesn't take much.