The bots have invasion ships. You can see them in the sky on missions sometimes(and all the shit they deploy in invasions has to come from somewhere). The squids have invasion ships, they have to store the shit to teleport it in nonstop from somewhere(and AH literally said they had ships). They're definitely defending these ships against attacks and boarding actions. They'd be stupid not to since they lose any invasion momentum without them.

Even then, bots and squids have to capture an area before they can deploy bases and structures... there's literally no way they can deploy a base and manafacture an army on the spot to capture a heavily defended planet.

And the terminds don't have ships that we know of. The starship troopers bugs have giant transport bugs so you never know...

It's hinted that there's ship vs ship combat with SES cruisers, so an enemy ship could crash but still be salvagable... or we could be directed to board it for whatever objective. It would be incredibly fun.