Brake Pedal Boot(?) Squeaking When Pressed

Today the brake pedal on my roommate's 2017 started making this squeaking sound. It looks like maybe a bit of fluid is weeping out?
Google Drive link to mp4 video with audio [LINK]
(Caution: video has an unintentional flickering effect in the lighting)



Is it an easy fix, or anything to even be concerned about?


More (possibly?) related info:
The shop we had previously taken it charged him to have the brakes serviced in October. My concern is all of the bolts were seized, and everything was encased in layers of rust. (I felt like an unqualified archaeologist chiseling everything out of there.) The slider pins and boots were dry and the pins rusted. The rubber ebrake boot where it connects is torn and crunchy on one of them.

All of the Brake Dust Shields are kaput. They're warped and rusted. I had to cut half one in half, it was so far gone.

I changed out the rotors, pads, and hardware on all four, but I need to go back and replace the rubber boots and slider pins on the other three of them.
(I didn't have the parts at the time and needed to put them back together for him asap.)

We used a torque wrench when tightening everything down to the specs in the Haynes manual.

The left/driver side front dust shield is very warped and I think it's scraping against the back of the rotor, but I can't tell. It's loudly squeaking and I can feel the shield shifting easily.

After I was done, he had Walmart double check the lug nuts were torqued down to spec, but they tightened them to the point I'm unable to remove them. I'm worried that I'll strip or bend the bolts if I keep trying. I plan to replace all the dust shields, but don't have access to safe equipment to do anything with it right now until we get home. It sounds terrible, but it's probably okay? I don't currently feel a difference is breaking power.

Once I'm home and pull the brakes apart to install/lube the pins and boots, I'll do this too:

Thanks for your kindness, patience, and guidance.

 

I appreciate it!
(I'll do a little housekeeping on the OP in a minute as well.)

Edit: oop, looks like I can't edit the original post. D:

Yesterday I pulled the wheel off and inspected the caliper, piston, pads, etc. It all looked good, save for the dust shield as suspected. I cut this side in half as well since it was caught up in what I think is the tie rod and rubbing a gouge into the rubber there. I think I got it before it got completely through at least.

Unfortunately, brake pedal still makes the chirp sound heard in the video from my OP. At least the owners says the scraping and squealing from the wheel hasn't returned yet!