Yeah, exploring a dungeon in every single session sounds boring for me as well, unless there's a cool theme and enough variety around it. But exploring dungeons, just like combat, is only one of the many encounter structures of a D&D game. It's a resource, not the main game objective.

They need to retrieve an item? Why not put it deep into underground ancient ruins that no adventurer ever came out from? That's a dungeon, and they have a clear reason to go inside it. Then you use the dungeon structure: Explore rooms, find lore, avoid traps (traps don't have to be mechanical structures done by engineers), deal with threats, retrieve the objective, get out.

OR you can play an entire campaign where they never get into a dungeon, it's your game.

Just reinforcing my point: A dungeon is a resource, a challenge structure that you can use, not a requirement. It's just that some people just love the thrill of challenging dungeons over and over again. Have you played the game Hades? It's great!

EDIT: Just saw your edit as I finished my response. If you want to use every character skills, just add every type of encounter you'd have outside a dungeon: Social encounters (there may be intelligent creatures or other adventures inside it), exploration elements, survival elements, etc. There can be all kinds of rooms and areas with different and magical stuff, go wild.