Yes, you can keep all the accounting records of the furniture you're selling while doing the interior design in one QuickBooks account. To ensure everything in your books is accurate, you can also work and consult with your accountant.
You can enter them in QuickBooks as inventory (furniture) and service (interior design) items. Here's are the steps to complete the process.
To learn more about product and service items in QuickBooks Online, check this out: Add product and service items to QuickBooks Online. This write-up will provide you steps on how to modify and track your items.
I'm only a post away if I can be of additional assistance. I'm always here to keep helping. Wishing you a wonderful rest of the week.