In the case of Uber, I think it's more likely that someone who's used their ride service may be interested in ordering food than it would be for someone who's u

In the case of Uber, I think it's more likely that someone who's used their ride service may be interested in ordering food than it would be for someone who's used Spotify for music to be interested in podcasts. I do think you're right that more subtle nudges are probably fine. Some might begrudge them but such promotions are a lot more tolerable than directly pulling an entirely separate app into your existing app and then placing the newly imported bits in the spotlight.