I consider that this figure can shed light on why there are many unprofessionally managed and failed e-commerce stores today. Especially over time, as barriers to entry have been lowered by content management systems like Shopify.
If you have a list of such companies that are of interest to you, could search for them by name in databases such as Crunchbase or Pitchbook. Alternatively, you could subscribe to Pitchbook or Crunchbase or such start-up databases and query basis industry and sub-segments therein.