Can’t track lost Apple Watch after switching to new iPhone

I lost my Apple Watch. It happened after it ran out of battery. Before I started looking for it, I bought a new iPhone and the watch wouldn't pair with the new phone. I've already erased my old iPhone. I can still see the watch in my account but not in the Find My app. Is there any way to get to its last location so I can know if it's even worth looking for?

[Re-Titled by Moderator]

Original Title: Lost Apple Watch, dead battery and new phone