We can create a new WH or use the existing one, but the main stream is to add the provision to allocate a particular WH for an employee, for this case, we can add a m2o type field from stock.location on hr.employee model. Thereby we can assign the WH location. Then under the Field Service module, need to add the provision for delivering the products, so for this case we need to inherit the stock.picking model and should make the source location is the location which have assigned for the same employee as default and Destination location should able to select the final one which they want to deliver.

Then validate the process, thereby it will automatically trigger one stock moves and finally the corresponding stock will decreased.

I have a similar scenario for a prospect and am thinking of having each service vehicle as a warehouse (or  warehouse  location) or  "mini -warehouse  location.  When replenishing stocks, do an inventory move from WH to service vehicle. From here I can setup POS for the particular service team and assign them to this "mini-warehouse location" so that they can perform offline sales for any products from within their "mini-warehouse location" to customer (this would be helpful particularly for dead spot areas of customer locations.  The Team can just sync up their POS when ever possible.
If needed, return of products from Service Vehicle to WH can be done in another move.
Has anyone done this successfully before?