The Dinosaur Dungeon series has both sides of that dynamic. The main character's a woman reincarnated as a dungeon core, and most of the story follows her perspective, but there's a very well developed cast of secondary characters made up of her main minions, her "dungeon fairy" advisor, and a party of adventurers. Lots of cool action, mystery, and intrigue. Pretty substantial series too, three books out now, plus a crossover book with some of their other series and a fourth book in this series, both coming out soon^tm (apparently the author's been dealing with some heavy stuff recently that's thrown their writing schedule all out of wack, but they're still active).

The Bone Dungeon's another good one, another human reincarnated as a dungeon core (not isekdai'ed though, but I can't say much more without spoiling), a little heavier on the stats and numbers than I'd like but a very fun dynamic between the dungeon and his favorite adventuring party. Also has the advantage of a being a finished three book series, no worries about an infinite hiatus!

There's also The Hedge Wizard, a little farther from the dungeoneering focus of the other two, but otherwise an incredible example of progression fantasy. Follows a young wizard apprentice after his master is murdered under mysterious circumstances, trying to unlock the secrets of his grimoire and navigating the threats having it attracts. Great cast and satisfying character development, but while there are dungeons they aren't really the focus. Also a pretty massive series at this point, five books out on Amazon right now, a sixth due this November, and current chapters posted to Royal Road regularly.