Not really. Using % of forecast area as % chance of rain inherently gives equal weight to your position being anywhere within that area. Even if you limit the forecast area to the 5m or whatever it is radius that smartphone GPS is typically accurate to which a weather app could theoretically do, simply using % of the forecast area covered as % chance of rain inherently gives equal probability of you being literally anywhere within that 5m radius. It would obviously still be more accurate, but those numbers wouldn’t be the same thing.