Don't hope. Don't guess. Use apps from F-Droid. There is still a risk at the app level but it is much lower. On iOS, there is no such thing so you can't do that

Don't hope. Don't guess. Use apps from F-Droid. There is still a risk at the app level but it is much lower. On iOS, there is no such thing so you can't do that. At the phone level, there are still opaque binary blobs, so don't trust blindly.