I agree with benjoshua's commentary, but there are creative ways to introduce these criteria using existing adventures, or by creating your own, which is a more involved and advanced approach.
Here are some ideas based on the criteria provided:
Level Adventure Special Interests Matched1 The Lichway (
OSRIC, White Dwarf #9 originally) Liches & undead, crypt-crawling, skeletal hordes, necromantic threat begins
The Lichway Project.pdf - Google Drive2 Maze of the Riddling Minotaur (M2) Solo adventure, labyrinths, maze dungeon with riddles and a minotaur
3 The Lost City (B4) The Mummy / Indiana Jones, buried ziggurat, desert ruins, secret cults, undead
4 Into the Fire (Dungeon #1) Young red dragon, portals
5–6 Dragons of Despair (DL1) Dragons, Sword & Sorcery
6–7 Tomb of the Lizard King (I2) Undead, traps, jungle tyrant, Indiana Jones theme, swamp, traps, lost relics
7–8 The Dancing Hut of Baba Yaga (AD&D 2E) Portals, labyrinth, planar puzzle-solving
8–10 Forgotten Temple of Tharizdun (WG4) Liches, undead, cultists, portals
TSR also published several Indiana Jones role-playing products that might appeal to her nephews.
Not all of the listed character levels match the original adventure recommendations. The "monsters" and encounters may need to be adjusted accordingly.
Some of these adventures can be expensive to purchase, but digital or print-on-demand (POD) versions may offer more affordable options.
There are many other great options out there. These are just a few examples to consider.