Querying if it's worth buying a JR Pass

Hi guys, I'm going to Japan with some friends from 2026-06-28 to 2026-07-18, and we'll be doing a fair bit of travelling about in that time. I've totalled up the cost for individual shinkansen tickets and I'm now wondering if a JR Pass might be a better option. The itinerary is:

2026-06-29 - Omiya > Sendai (Miyagi)
2026-06-30 - Sendai (Miyagi) > Omiya
2026-07-04 - Tokyo > Nagano
2026-07-06 - Nagano > Kanazawa
2026-07-07 - Kanazawa > Osaka
2026-07-08 - Osaka > Himeji (returning same day)
2026-07-12 - Osaka > Nagoya
2026-07-13 - Nagoya > Kyoto
2026-07-16 - Kyoto > Tokyo

Within these points we'll be using the local train or bus networks to get around as well. I just wanted to check if a JR Pass covers all of these routes, and the process of reserving seats on the shinkansen? Or if there's a more cost effective method (i.e. paying for the Omiya / Sendai tickets separately, then getting a shorter length JR Pass for the rest of the trip)?

Thanks in advance! :)