I am a firm believer that anything can be sold online.
Granted, some types or products and services are a better fit for Internet selling than others; however, I believe that every business needs to have an online presence online.
If you don't believe what I'm saying, think about this: What product or service couldn't be marketed online? What business couldn't include their name, address, phone number, fax number, web site URL, and product or service description online? What business type couldn't advertise what they do online and benefit from it?
Sure, there are some businesses (like car sellers) that can deliver their product as a download or mail order item. However, product or service delivery isn't a prerequisite for an online business. There are still lots of other aspects of every business that can be conducted online.
I would be surprised if there are any major car dealerships in your region that don't have a web site.
Let's spend a minute and see what kinds of businesses thrive online. If we can identify these, they may be a great starting point from which you might decide upon a business niche to enter solo business for yourself.