The application should be able to prevent the app from loading at boot and managing this status as frozen or not (e.g. in a list). That the application requires root privileges shouldn't be a problem.
Examples of non-FLOSS apps are AppFreezer and RootAppDelete.
Where I tried searching:
- Searching Google PlayStore for FLOSS apps is useless because Google providing a way to uninstall the pre-installed advertisement wouldn't make sense.
- F-Droid doesn't return any results for the search query "freeze".
- Android forums are very hard to read due to the lack of structuring a Q&A provides (I searched 20 posts in 4 forums for any helpful content and gave up).