To be clear, this isn't a choice-of-law case. It's not about whether California law applies. It's about whether a court in California has jurisdiction; that is, whether it can hear the case at all.
It also isn't against the Californian company. It was Shopify which is not a Californian company.
Seems bizarre to me that several lower courts ruled in favor of Shopify though..
Could a tort claim under California state law be heard in any other court (assuming no accompanying Federal claims)?
That seems like a meaningless distinction. If you can't have a case heard by a state court, then that state's laws can't be applied, by definition.