We are a long way away from these things if they ever happen, but there is an interesting convergence in technology that might happen in the long future. Basically, nano tech already exists, but we did not make it. Cellular life checks all the boxes nanotech aims to achieve. It is highly likely that if nanotech ever enters mainstream usage (consumer products, building materials, etc.) it will take the form of bio-engineered cellular life, not tiny robots. Why make your own when you can just hijack the existing proven platform? It's not likely this would take the form of large-scale plants, rather in microscopic things like fabrics, adhesives, maybe even data processors (so called wetware computers). Though it might happen that we use cybernetic engineered "animals" with remote control tech embedded into them for certain labor/exploratory tasks as self-maintaining drones.

IMO it's far more likely we achieve near perfect mastery of biology before we ever have serious civilization on other planets, even within our own solar system. Once we have that much control, it's just another form of machinery/tech.