It depends on what you're willing to be public about. I think your OKM is people buying something and looking at all the metrics around that.

Great metrics for e-commerce are churn, lifetime value, repetition of purchases, average revenue per user. On the marketing side, I think it's useful to understand what kinds of marketing produce certain kinds of repeat revenue.

Publicly, I think understanding how many customers purchased something in the past 30 days is useful. Potentially, the number of customers that purchased something above $X.