To actually manually craft a first tier robot requires a spidertron and blue circuits, so it's not helpful in early game this way. I checked you do start with one without Hextorio; it's not in inventory but placed in the world like a spider-vehicle (already placed for you).
This is caused by Hextorio's initialization. Nauvis gets deleted and recreated, which means the free companion is destroyed. But I can add a compatibility, thanks!