These days, potential customers look for businesses in many places across the internet. If the business doesn't show up where a customer expects to find them, or if the information is wrong, the customer loses faith in the business. On the other hand, if the business name and correct information and some great images or videos show up in the search results, customers view the business as trustworthy and are more likely to make a purchase.
The Online Visibility business is booming because of that. There are literally hundreds of directories and other sites where a business needs to be found. Some of them are very well known, like Google My Business Pages, and some are less prominent but important locally, like a local news site.
You will be providing a service of getting the business listed on all of these sites then making sure the information is kept current. There is software available to make this easier.
Most providers of this kind of service charge a set up fee in the neighborhood of $500-$900 then an ongoing monthly fee of $67-$97 to maintain the listings.
The start up costs for this business are minimal. You'll need a website and some initial content and search engine optimization for your business. You can do this yourself for very little cost or you can hire a fellow solopreneur to do it for you. You may want some printed marketing materials, such as business cards.
The ongoing costs on this type of service is minimal. The software to create and maintain the bulk of the listings costs less than $200 per month. If you join a networking group, there may be some costs for that, and you may decide to run some ads.
All in all, this is a good starter business, it isn't complicated to learn and it's a service every business either has to do for themselves or hire out to someone else.