How to create a Local Product Inventory Feed
First of all, you must ensure that you have a Primary feed in Google Merchant Center.
You should create both the primary feed and the local inventory feed on the same app to ensure that product information is consistent between them.
Then, you check and follow the below steps to create the Local inventory feed,
1/ Enable the Local program in Google Merchant Centre. Depending on Google Merchant Centre country you might find it in Google Merchant Centre left menu, Growth > Programs
3/ Create the feed, select Special feed type and choose Local inventory feed under the Metadata tab and paste the store code there. Then, complete the local inventory feed as normal.
4/ Once the feed is submitted, you might need more steps to complete in Google Merchant Centre for the local program, including inventory verification, etc.