Map Update method/resources?

I've taken the plunge and replaced my defective nav unit with an incredibly expensive used item. The maps apparently have not been updated since the vehicle was manufactured, which puts it at least five years behind the failed unit previously installed.

The nav unit update button indicates that it can be updated from a USB drive, but my searches here and on the world wide interweb return little of value.

How can one acquire the necessary data to place on a USB drive?
If one can get a map update from Toyota Entune (still operating?), is it possible to purchase only the update or even just subscribe for a month to get the update loaded?
Regarding the previous questions, can I get the update on a flash drive and update both of our 2013 Rav4EVs?

I didn't realize how many of the features of the navigation unit I missed, until they were gone for a week (not missed much) but then returned now (wow, I forgot how useful this is!)

You can buy the map update from Toyota. However, I doubt you will find it worth the asking price. Mine has never been updated since new and I don't miss it. If you live in an area that has had a lot of construction with new roads and subdivisions, it might be worth it, but I prefer to just use my phone and Google Maps if I care about traffic routing, etc. The head unit could never do that even when the data service was active. I just showed heavy traffic areas on major freeways. It could never change the routing based on traffic like phone apps can.

The only time I use the car's navigation is when I am on a long drive and I want to quickly compare the distance to destination to the remaining range.