When I set up my workflow for a project I'm working on, I didn't set it up as a reusable workflow (first time using SharePoint Designer and working with workflows), and now I would like to transfer my list and the respective workflow over to another site I have created. I was able to export the workflow to a .wsp file but now I'm not sure what to do. After some research online there is a suggestion to add the "Solution" into SharePoint online, however it appears that some of my settings aren't matching those that I'm seeing in the suggestion posts, even though I have full access of the site. Any help would be appreciated.
You can save your list as a template, download the template on your PC and upload the template to the desired list gallery.
Use this article to follow the steps https://support.office.com/en-us/article/Manage-list-templates-c3884ad1-bc49-44b8-b3d6-3bc6a01eb393
Also, I have moved SharePoint Designer workflow many times from one site to another using the below article.