Sounds like it would be higher than I expect, but I still claim it can not be more than fractions of a percent. Actively toggling a setting like is definitely esoteric behaviour even for a power user, never mind the large masses of smartphone users.
Unsupported Android version is not related to old app versions, Google Play will still work.
I do grant that web is more likely to be up to date than an app. Me claiming that it depends on the developer was just being pedantic: technically it depends on the developers and their release practices, but likely it's the web version that is more up to date.