Expert Only: Create Shopify CSV files from excel data

We have an inventory of 6000+ products in excel file. We have all the specs, name, sku etc... In another file, we have the images link for each product. We need a shopify expert to build the CSV ready-to-upload file from this data. - We have a template to use for the description. All specs must be integrate. You also will have to link many products data together before to create the csv file. Many product name have the same sku. The goal is to link them and create 1 product in the csv file. By example, a battery may work for many different device. We work with excel. If the description lenght is too large, this may required to find an alternative for the longer's one. For this products, you may have to find a solution to avoid to block the project ( ie: manually upload, direct upload to shopify, other software, etc... ) Only apply if you know to create shopify csv file and have expert skills in data manipulation.