Am I able to upload an excel document that we build all of our proposals off of and use it for line items in HubSpot Quotes?
Hi @AWells5! Welcome to the Community-- happy to have you here 
As long as your import files are set up with the required fields to create line items, you can import them to deals to create quotes.
Let me know if I did not understand your questions or if you need additional clarification!
Best,
Kennedy
Hey Kennedy,
I have seen where you can do that but does it work for quotes and individual line items?
This might be better achieved by adding associations with the Quotes API. You cannot import line items to quotes because they must be imported with Deals. Line Items need an associated commerce object (e.g. Deals, Quotes, Payment Links, Subscriptions, Custom Objects) with the standard import tool.