“I think very few companies have success developing a second app you no matter the size of your first... Even Duolingo... they launched I think it was either chess or math as a separate app and then they had to bring it back into the main app”

Expand the app — don't spin off a second one

Resist the "let's spin out a sister app" instinct. Even Duolingo failed at it and pulled the standalone back into the main app. The filter for any new feature inside an existing app: (1) does it solve a real pain users already complain about, (2) does it overlap with your existing audience, (3) do you have permission from your brand to enter that adjacency? If yes to all three, ship inside the main app and lean on orchestration to surface it.