Q: Did my photo files move to external drive?

I previously kept two iPhoto libraries, a MASTER on external hard drive and one on my Macbook. So I think I have moved/converted/migrated(?) everything to a PHOTOS app on the external drive.

But how can I be sure the photos are really there before I delete from Macbook? How can I find my jpg/nef files if I can't use finder nor the new referenced file?

Beginning t question my decade long allegiance to APPLE.

Thanks for any help provided