Can anyone tell me where (specifically) the turn signal flasher is located on a 2010 - 2012 FUSION?

The actual flasher relay that makes the turn signals turn on/off.

I keep reading that it's a blue relay to the left of the steering wheel, but no such part exist.

I can hear it but cannot feel it or see it anywhere...

 

Flasher relays are for vehicle made in last century and early 2000s. The blinking of the turn signals is handled by BCM (body control module). If you upgraded to LED bulbs you need to add load resistors. If you didn't switch out the bulbs, do a BCM reset might fix the problem. Note that disconnecting the battery ground probably can't reset your BCM, you need a capable scanner like Foxwell NT510 Elite.Last resort, find a seller on ebay, tell them the issues, ship them your BCM so they can repair for you, since it's the exact same one, so no reprogramming is needed.

 

Some flasher units are mounted to the passenger side of the steering column assy. You can hear them work , but have no idea of where they are.
Some electronic flashers are pushed into a plug behind the dash between the steering column and the radio.. This is where patience pays.

Can we ask just why you are looking for this flasher ?

 

My OEM headlights were scratched so I bought some aftermarket headlights. They have sequential turn signals built into them, similar to Mustangs. However, the sequential part moves so fast that they don’t look sequential at all, and I wanted to slow them down a bit.

So I bought an adjustable flasher like the one shown below, and I wanted to plug it into where the original flasher unit was plugged in.

Wevdn Electronic Flasher
https://a.co/d/5sPhO2k

 

Then your headlights are not compatible with your car. You need to return it and buy one that's compatible. Often the sell price $300 vs $800 makes the difference.
So what you are doing is just the same as upgrading to LED bulbs like I mentioned previously, you need to locate the turn signal wires and add load resistors to slow down the speed. If all the wires are integrated into the headlight you have to disassemble it which I don't think you want to do that. If you already bought the CF-13 flasher relay with adjustable speed, you probably need to return it when your car doesn't have one.
If you can locate the 2 turn signal wires from your new headlight connector, you just need the power wire, cut and connect that to L terminal on your flasher relay, the B terminal on the relay connects to the other end of wire, the power feed. By design the pins of a flasher relay should be plugged into something but not always necessary. You just need to position the flasher relay within the turn signal circuit, somewhere inline in between.
If you can't get to the original flasher relay (assuming it exists), it doesn't hurt to add your CF-13 in between. Just like double fuse on a single circuit, doesn't hurt anything.

BTW does the blinking speed on the back blinks at normal speed?