The above solution can be used with Odoo version less than or equal 14.0 but with version 15 and above you can't use it.

Solution: is to import the product category with excel as below:
id parent_id name

product_category_1 All saleable

Then access the DB with Pg Admin and execute the below command:
# This to query that the record is exists
select * from ir_model_data where name ='product_category_1' and model='product.category';
# This update to update the module to product:
update ir_model_data
set module='product'
where name ='product_category_1' and model='product.category';

Then you can install Point of Sale. I have tested it before writing my answer.