It really depends what you define as a limit versus what the platform was created to do? The simple answer to your question is yes you could build an API that runs an E-Com site. How specific vs general you design it is up to you.
Warewolf provides the relevant tooling to perform the various functions your E-Com site would need i.e:
I think the team would be better position to support you if you had a more specific requirement or example of what you were actually trying to achieve.
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