So we now know about the Variant Dungeon formula:

All Variant Dungeons will have one NPC to explore the place with you.

All Variant Dungeons will have exactly three pathways at the beginning to choose from, each leading to a hallway with two bosses.

The first boss on each path is the same for all paths but with varying mechanics.

There is a fifth, hidden boss that requires you to solve a riddle by running the dungeon multiple times to find different clues in the logbook entries.

There are exactly 12 entries to get by running various modifications of the three routes, triggered by certain actions.

So the only things that will really change between the Variant Dungeons are the mobs and bosses and the aesthetics. The formula itself is always the same, just like it is with normal dungeons. So don't expect to be surprised by anything other than that.