I think the Ninebot Max is a good suggestion, but main drawback will be lack of suspension. Its large pneumatic tires do help quite a bit though and the scooter is very durable.
I haven’t checked out any of the Kugoo scooters, but price versus features look pretty good.
I think going straight to Alibaba is not a bad idea if you want to stay under your budget and gets something more powerful. Keep in mind, you’ll need to be willing to do repairs (or find a local place that offers them) yourself.
If you do go the Alibaba route, I’d look at the Kaabo Mantis lineup and see if any of then are in your price range. I think the Mantis base version with 10-inch tires is the best option and its suspension should be good enough for rough roads. They have a bunch of variants .. some single and others dual motors that will increase/decrease the price.
I agree that the Widewheel is probably not the right scooter for your roads.