Is there a high demand for French when immigrating to France? Is it unreliable to immigrate to France without contact with French at all?

That depends on what the landlord did when he immigrated to France. If you are doing research or investigation, you must have a lot of professional exchanges with many French people, so the landlord's French terminology must be very good. But since the landlord has never been exposed to French at all, he may just go there to start a new life. Of course, the French speak English, so as long as the landlord's English is good, then the basic daily communication will be no problem. But if the landlord wants to look less weird, he can sign up for a French zero-point immigration class, which is provided by Beijing Qijin French Training School. This is of course no problem when dealing with French communication in daily life.