Best fan controllers for PC builds?

Hey there—I was wondering if it’s actually possible to run a fan controller without even having a PC hooked up? Like, could I just wire it directly to a 12V Molex adapter instead?
If anyone out there knows a way to pull this off, it would honestly be a huge lifesaver for me. 😁

Maybe something like this?

Or this if you need something a bit more aggressive..

So, I’m thinking along the lines of something similar to this other setup—let’s say we’re looking at a 4-channel configuration—but here’s the kicker: I want it to plug directly into a standard wall outlet instead of being tethered to a PC. Does anyone know if there's a way to actually pull that off?