Alex here, from the Shopify support team.
There absolutely are apps that can help with this! A few that I've managed to dig up here are:
These should all allow you calculate cost of goods and profit, as well as organize by vendor/supplier - you'll just want to look through the apps themselves to see which one will work best for you and your business. You can also try them out during their free trials, just remember to remove them before the end of it if you decide not to use the app! You can do this by heading to Apps in your admin and clicking the trash can beside the one you'd like to remove.
I hope this helps! If you have any other questions about this, you can reply here on the thread. You can always reach out to our support team directly for app recommendations as well!
Alex | Support
My app Simple PO https://apps.shopify.com/simple-po was specifically created for this, not only does it display all the info you need but lets you create purchase orders to send to your suppliers, and you can generate them automatically from orders.
Happy to answer any questions
You can also check out Data Export. Data Export is a reporting automation tool to report sales, inventory, refunds, tax, billing, fulfillment and many more custom reports.
You can update the cost of product in a Google Sheet. Data Export will fetch the data from the Google Sheet and create profit and cost reports.
Let me know your questions related to COGS or reporting.