I'm prepping my truck for sale and want to make sure it's mechanically sound for the next buyer. I was finishing up a 2 hour roadtrip, pulled in for an oil change at the shop near my house. Upon arrival, the truck sounded like it was about to give out. No pinging or metallic noises, but more of a grinding. I was shocked because the MPGs were normal, no CEL, and I couldn't hear or feel anything strange at highway speeds.

At first I thought maybe it was something catastrophic, but it sounds to me like it's limited to the front of the engine, maybe the idler pulley bearing? If you watch the video, you can see idler #2 has a slight wobble occasionally. Why would only that one part be failing, and would it be ok to just replace that one part? I know the 2UZFE is practically bulletproof apart from the waterpump and timing belt maintenance, but I don't want to sell my truck if there are hidden issues. I also don't want to replace unnecessary parts, so looking for recommendations. If it's a simple pulley then I can do it at home, but if this is a sign that the waterpump and timing belt need to be done, then I'll have to bring it to a shop

https://www.youtube.com/watch?v=3IFMs3o5qoM