There's a lot about it that isn't great. It treats Go like a scripting language, it's got no structure (1000+ lines in a single file), nothing is documented, the models are flat, no methods, it hard codes lots of strings, even the flags are string comparisons instead of using the proper tool, regex compiles and use inlined, limited device support based on some pre-configured, hard-coded strings, some assumptions made on storage device speeds based on its device name: nvme=fast, hdd=slow, etc.

On the whole, it might work for now, but it'll need recompiling for new devices, and is a mess to maintain if any of the structure of the data changes.

If a junior in my team asked me to review this, they'd be starting again; if anyone above junior PRd it, they'd be fired.