Can I use pre-ground coffee for espresso?

It depends entirely on which basket your machine came with, and the answer changes completely between the two.

With a pressurized basket

Yes, and this is what those baskets exist for. A pressurized (dual-wall) basket has a small hole behind the visible mesh, and pressure builds against that hole rather than against your coffee. That makes grind size almost irrelevant — you get a crema-like foam from supermarket pre-ground.

It also means the coffee cannot get much better, because you are no longer extracting through a coffee bed in the normal sense. This is the trade every entry-level machine makes.

With a normal basket

Almost never satisfactorily, for two reasons.

It is usually too coarse. Supermarket “espresso ground” is typically ground for moka pots and pressurized baskets, which is coarser than a non-pressurized basket needs. The result is a fast, sour, thin shot.

You cannot adjust it. Dialing in espresso means moving the grind in small steps until the shot lands in the right window. With pre-ground you have exactly one setting, and if it is wrong there is nothing to do about it.

The freshness problem, which is worse

Ground coffee loses most of its aromatics within about fifteen minutes. A bag ground in a factory weeks or months ago has lost the CO₂ that makes crema and most of what made the coffee interesting.

This is why a grinder is the purchase we recommend before the machine. A modest grinder with fresh beans beats an excellent machine with pre-ground, reliably.

If you have no choice

Buy the smallest bag you can, keep it airtight and opaque, and use it within two weeks. And if your machine takes both baskets, use the pressurized one — it is the honest tool for the job.