I strongly disagree that Shopify is only good for "companies with few SKUs or mom-pop kind of stores". Perhaps that's where they started out, but their Plus offering is very solid these days and provides a good platform for retailers of all sizes.
I run an agency that's highly specialised in Shopify, so obviously I have a dog in the fight, but as someone who's recently helped migrate a business with ~$6b/year in revenue to Shopify I think it's time to retire that particular misconception.
Having used shopify API and the new graphQL API I am sure shopify is for small business and then you need to rebuilt the system from ground up using partners to support any complex case. In Shopify collections and categories are not represented as graphs but as distinct entity relying on application code to make this link. Media management API is so worse than can be done with many opensource system like Saloer or Sylius or Spree. Same is the case when need to support multiple price lists for specific supplier or buyer. When it comes to data based security based on user role, one has to roll out their own system. After doing all that custom application code still do not have access to the API server code.
So for a partner it guarantee regular stream of revenue but at the cost of customers’ interest who is now at the whims and mercy of company which wrote the custom code and also shopify which control the core API server code.
If you want to built a reliable and resilient system for 6 billion business a custom built based on open source is far superior to proprietary and black box of shopify+closed custom code written by partner.
I run an agency that's highly specialised in Shopify, so obviously I have a dog in the fight, but as someone who's recently helped migrate a business with ~$6b/year in revenue to Shopify I think it's time to retire that particular misconception.