I like this idea better than the banner ads at the bottom of an app, especially if the l5 load times are anything like the pinephones, that splash screen would be up for a non-zero amount of time. And by having it be a sponsor that allows the developer to decide what they want to be associated with. By being associated with the developer there’s a decent chance it will be related to the interests of most like-minded customers/users without any information or feedback from them. Sure, some people this won’t be relevant for, but I do think this strikes a balance that the people willing yo use ad funded applications wouldn’t hate. (The people unwilling to use ad funded apps at all opinion on this is irrelevant as they wouldn’t use the apps that have this anyway).
I do think it would be appropriate to have some sort of indicator to filter on to show/hide apps with this functionality, but I do think this is a reasonable middle ground.