JR Pass and what to do on early arrival

January 5
We are going on the April 22 Tauck Essence of Japan trip. We are going early for 4 days and plan on sightseeing locations not covered by Tauck. For previous travelers, are there any must see locations not covered by Tauck in Tokyo. We are not planning on going out of Tokyo over those 4 days.

We have T-Mobile phone service. This has served us well in Europe and South America. I can't see any purpose for an e-sim or similar. Any thoughts on that subject?

Is there any reason to get a JR Pass if we won't be leaving Tokyo? I have Passmo on my phone and can load that in the train stations. We welcome your thoughts.

Thanks and looking forward to meeting those who are going with us.

Glenn & Patty Camp