Building a Location-Based Grocery App: Need advice on geo location

Hey All,
I'm working on a grocery app where I need to implement location-based features. Here are my current challenges

Get User's Exact Location: I need to accurately capture the user's location to show sellers around them.

Define Seller Area Radius: I want to define a radius around each seller and give it a meaningful name (like "Zone A" or "Downtown Area"). If the user is within that radius, their product feed will be populated with items from sellers in that specific area.

Delivery Tracking: I also need to track the delivery person's live location and show it on a map for real-time delivery updates.

Tools I am using Spring boot for backend and React for frontend.

Any advice, tutorials, or similar experiences would be super helpful! Thanks in advance for your input.