you can't really get that accurately anywhere
You can get 100% accuracy of impressions/keywords from GMB insights.
About 30% of local and non-local mid to low volume keywords will not show on tools but will inside Insights.
Verify a GMB in the center of a high population city for your target country you want to collect keyword/search volume data.
For example, New York City has a population density of 29,302.37/per sq mile. Average GMB proximity ranks for 25 miles, so approx 73,2559 people.
Toss up your niche GMB, optimize to rank for as many different keywords as you can, add reviews that include your keywords ect.
Take the keyword impressions/clicks data you see over a 30 day period, for example lets say 1,000 impressions and 10 clicks for XYZ keyword on the GMB.
That is 0.14% (1,000 out of 73,2559) people who searched the keyword. Now take that impressions per population data and apply it any other city population you want to find highly accurate search data.
Example; Miami has a population density of 1,004.8/sq per mile X 25 miles = 25,120 people. 0.14% of 25,120 is 351.68.
So you can expect approx 351 of search volume/impressions for XYZ keyword in Miami (25 mile radius from DT core).
Same math can be used for whole cities, states/provinces and the total country.
There are things that can skew data of course, some types of niches are more likely to be in major cities and not rural so be mindful of that.
There is no tool available that I know which can accurately show raw search volume of all keywords in hyper local, so I developed method above and just use G auto suggest scraper to find keywords for testing.
appreciate it