Press sauté button on Instant Pot.
Add beef to pot and cook, stirring occasionally, 5 minutes.
Drain fat from ground beef.
Sprinkle beef with flour and taco seasoning.
Pour in beef broth and mix.
Bring to a boil and let cook 5 minutes, until sauce is thickened. Stir occasionally.
Turn Instant Pot off.
Scoop 1/2 of meat mixture into a (7-inch) cake pan.
Spread 1 cup chips over meat.
Top chips with 1/2 cup cheese.
Repeat with remaining meat, chips, and cheese.
Cover pan with foil.
Clean inner pot and put back into Instant Pot.
Add 1 cup water and trivet to Instant Pot.
Create a foil sling and carefully lower pan into Instant Pot.
Close lid and set pressure release to sealing.
Press manual or pressure cook button and set to 7 minutes.
Allow pressure to release naturally for 10 minutes. Quick release remaining pressure.
Remove pan from pot and serve with sour cream as garnish.