Access orders with own products
Yes, you can use Views as Patrick suggests. Make it a View of Order entities with relationships joining Orders to Line Items and Line Items to the referenced Products. You can then apply a contextual filter to only show results whose Product uid matches the currently logged in user's uid.
A couple things to keep in mind...

Such a View would need to &quot;Disable SQL rewriting&quot; in its advanced settings, because it won't work so long as normal entity access control conditions are applied to the query.
You should include in the View itself all the information you need the course seller to see rather than trying to link them directly to a standalone page per Order. If that's what you want, you're going to actually need to hook into the access control system via custom code.