Hi Darshan,
if distance calculation doesn't need to be accurate the you could use the SQL Server built in Spatial queries. Distance is calculated in a direct line and not based on roads asf.
The example here is an advanced sql server query (not possible to achieve this with an aggregate). It takes Latitude and Longitude as parameters. Both are of type decimal with a precision of 8.
Within my Entity Geo i have stored cities along with their latitude and longitude. Also both a decimal with a precision of 8.
geography::Point(Latitude, Longitude, 4326). This function casts both decimals to a Point SQL data type. 4326 is a spatial reference identifier. In short this one is responsible for how results are returned. 4326 is metric. You can read here Spatial Reference Identifiers (SRIDs) - SQL Server | Microsoft Docs more.
The appended .STDistance which also takes a geography::Point as parameter calculates the distance between the two points. With a spatial reference identifier of 4326 this returns meters. As you see in the example i divide that by 1000 to get kilometers, wrapped in a ROUND with a precision of 1.
For displaying geo data on a map, you might find the LeafletJS project helpful. There is a forge component for reactive web available here LeafletJS - Reactive - Overview | OutSystems .
For finding places i can recommend what3words (one of my favorites) https://what3words.com/. Still there is no forge component available. I might do that when i find some time :-). what3words is free for small companies but they charge a price when transaction volume rises. The website does not say when this happens.
Hope that helps,
Stefan