I am no expert, but yes, it's flakes for my projects. It keeps the build time tooling separate (eg Go compiler, node version,etc) from the main system (so I could for example have different versions for different projects). It also makes it easier for others that might (one day) contribute to my projects to start developing (assuming they're using nix) with the same tooling and versions that I am using.

aiui, nix shell was the non-flake way of doing things and nix develop is for flakes (this is probably a gross over simplification!)