The “Angry Astronaut” did a video from Boca Chica showing the Raptor work station being moved towards Ship 26:

https://www.youtube.com/live/MmUwHVji9b4

He says that’s only done if you are installing engines on the Starship. You don’t do that if you are only doing pressure testing. He notes though that it could be putting engines either on S26 or S25. Probably we’ll know by the end of today which ship is having engines installed.

Conceivably, it could only be doing static fire testing. Still, 6 engines are sufficient for it to take off fully fueled. Note, the expendable version is much lighter than the reusable version, having no top or bottom flaps, heat shield, legs, or ballast tanks. Any reasonable estimate of the dry mass of the expendable version allows for it to reach orbit with significant payload in a single stage.