I'm afraid that's beyond the scope of the site Peter. You would probaboy need to use mapping software that runs locally on your computer to carry out advanced tasks like that. It's hard to an online app to handle large volumes of data, such as plotting 500,000 points on a map.
I know the site is called plotaroute but somtetimes I would like to just plot out on a map where I have been. for an example what streets in a city I have walked and which one I have left yet to be discovered. Not necessarily a route. It could be just layers or lines.
Now there is an option to show up to 30 routes in a map. And every route has a limit to 50000 points? I would like to just plot how many sections/layers/lines I want, but the limit could be 30*50000=1 500 000 points instead? The sections don't need to be a A-B-route, just a line on a street that I want to show that I have been walking on.
I tried to achieve this in Google Maps, but there is a limit in layers so I had to stop.