I got the same issue with old man emu leaf springs. All that I have done is spay them with Silicone WD40. Nothing, still the same squeak. Have you done an update to this video? I only drive my 2020 TRD Off Road 4x4 on the weekends.
I don’t think those factory ome bushings will work with the gressable bolts. When I ditched the noisy factory springs for rough country 3.5in packs I brought a set a doberson’s gressable pins and bushings. Worked super well but the bushing set is pricy.
I think what causes the squeak are the bushings rubbing on the front mounts. I had this problem just 2 months after my BP-51 and Dakar leaf springs were installed. When I spray silicone grease on the front mount, the squeak goes away for a few days until the spray grease dries up. I also replaced my shackles with OME, got New set of bushing even though the bushings that came with my suspension set were also brand new, and also replaced my bolts with greaseable ones. Nothing worked. I got tired of it so I just installed back my stock leaf springs and just replaced my shackles with those extended ones. This solved my problem because I noticed, the ford ranger stock leaf springs have longer sleeves inside the bushings so the rubber bushing itself doesn't rub on the mount.
Not sure if you figured it out but I have the same issues and in between each leaf there are little yellow pads I jacked the truck up and put some water proof grease where the pads are and it stopped squeaking
I have the identical creaking noise in my Land Cruiser 79. Solved it by spraying WD40 Dry Lube in-between the leaves, especially at the ends where they override each other, and the bushings. This sorted it out! For how long, I don't know!
Your springs should’ve came with poly bushings for the front eyelet and then both eyelets for the shackles. Load the suspension and torque to spec all bolts