Ok, I also found this video and this does sound like my tapping sound. It's diagnosed as a rod knock in this video, and it doesn't start/stop like mine. I didn't see anything in the oil and pan, but it may be because she didn't drive it once it was heard.

https://youtu.be/FW42V5au7Vs?si=BuTN55tMDpiG8z9a

I'm just not seeing any knock sensor faults or anything else which is weird if this is it