My thinking is that the house was originally wired for a doorbell, but
for some reason the homeowners' decided to go with a battery operated
doorbell. I just can't find the wires inside my home that would connect
to a doorbell box.

I would love to have a wired doorbell.

I had the exact same issue, had no idea where the transformer was or
the doorbell wires

One day I talked to a neighbor, looked at where his doorbell and
transformer was went back home and found mine in less than 15
minutes

Good thing too the doorbell transformer buried under a cieling was
VERY HOT, smelled of smoke I powered off the house and discoinnected
it after letting it cool for awhile, so I wouldnt get burned

A week later I had my new doorbell chime working

Make friends with your neighbors you can learn things from them