In large bowl, mix together ingredients for ricotta filling. Set aside.
Set Instant Pot to Sauté mode. When hot, add ground beef and sausage. Brown 3 to 4 minutes, breaking up meat with wooden spoon. Add diced onion, Italian seasoning, salt, and pepper to Instant Pot and stir quickly. Cook 2 additional minutes.
Remove meat from pan and clean IP.
Starting with marinara, layer all lasagna ingredients in springform pan, alternating until all ingredients have been used. Layers should be marinara, lasagna sheets, ⅓ of total ricotta filling, ⅓ of total ground beef mixture, and ⅓ of total marinara sauce.
Repeat step 3 for a total of 3 layers of each ingredient, then top with shredded mozzarella.
Cover pan with aluminum foil. Use Instant Pot trivet to lower pan into Instant Pot, then cover pot with lid and secure with vent in Sealing position.
Set IP to High Pressure and cook 24 minutes. After cook time is up, Natural Release pressure for 10 minutes, then carefully Quick Release. Carefully remove trivet and springform pan from Instant Pot.
Optional: Place pan under broiler for 3 to 4 minutes to brown mozzarella cheese. Serve hot.