Yes that's correct, there is no standard action from a Sales Order to a Project. The standard link goes the other way, Billable planning lines create the sales invoice.
Before building anything though I'd first confirm what the process between the sales order and delivery actually is. If it's manufacturing or assembly, BC already supports that from the sales order through Order Planning or Assemble-to-Order, so a Project could just duplicate it. Projects make more sense when you really need project budgeting, resource planning and WIP.
If a Project is required, then I'd build an action on the Sales Order that creates the Project for the Sell-to Customer, a task per sales line, the planning lines from those sales lines, and stores the Sales Order No. on the Project so you can navigate back.
One thing to settle early is billing. Decide if the sales order or the project invoices the customer, otherwise you bill twice.
Glad to help - follow up if anything is unclear.
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Regards,
Grigorios Mavrogeorgis
Business Central Consultant & AL Developer
Work: Gmsoft Limited
Blog: insidebusinesscentral
LinkedIn: linkedin.com/in/gregorymavrogeorgis