I think it depends on the type of startup. What is the business, industry, target market, competitive landscape? I am not sure there is a simple answer.

If a startup is in deep tech or sciences they may want to prioritize hiring the best talent first and foremost. If it is a consumer good, they may want to prioritize perfecting their product first and foremost. If it is a service business they might want to prioritize their sales funnel and delighting early customers. If it is a software business they might want to prioritize getting bugs out and customer acquisition.

This is all assuming the startup has some kind of initial economic viability either via seed money, or loan or founder investment. If they have no money to get off the ground then securing initial financing should be the priority.