RFE most likely not interview
Most likely (as is the practice nowadays) you will get an employment RFE.
First off, you do not need a H1 from company B. All you need at all times is an employment offer letter from company B, the offer being valid after GC approval. You might need to generate a fresh letter when you get the RFE.
The problem is, if you applied for EAD but is still working for company A, you need a valid reason. EAD is enough for you to go and work for company B and so you will be questioned why you did not do so (or why you did not apply for EAD)