First concern is whether there are LTIs or options that your school district uses, but the University doesn't. For example, if your school has DesignPlus but the University doesn't, then any pages you make with their tools may not work.
This may show up even within "vanilla" Canvas, where there are Classic Quizzes vs New Quizzes: my University only enabled the New Quizzes this year, some Universities have already blocked Classic Quizzes, and others may still not have New Quizzes enabled. Luckily, these can usually be converted, for most types of questions (see How do I migrate a Canvas quiz to New Quizzes? - Instructure Community - 991 for some details)
But assuming that there are no issues with different features, it is possible to export a course as a zipped archive, and then re-import it in the new Canvas instance:
Instructions on exporting: How do I export a Canvas course? - Instructure Community - 785
Instructions on importing: How do I import a Canvas course export package? - Instructure Community - 795
You can also try building the course in a Free For Teachers account, which lacks some features (such as New Quizzes), but would avoid you having to ask for a Sandbox course at your district.