A month ago, I had onsite interviews lined up with two large software companies, Company A and Company B, with Company A being by far my first choice between the two. Both companies are located in the same city, thousands of miles from my current residence. I would have had the interviews close together, however Company A rescheduled my onsite interview at short notice for a month later (which is this Friday).
In the meantime, I had my onsite with Company B and received an offer, with a speedy reply expected from me (certainly couldn't delay it a month); it was good enough to quit my current job (so technically I am unemployed, having served my notice period). Still, my employment with Company B isn't 100% until I sign their non-compete agreement, and they won't show me their non-compete (nor give me an opportunity to sign it) until a few days before my start date.
My start date with Company B is scheduled shortly after my onsite with Company A; I'm told to expect a hiring decision from Company A about a week after the onsite. I'm currently in the process of relocating to the city that contains both Company A and Company B, with a small financial grant from Company B to support the move (which I will fully forfeit back to Company B if I renege).
In the event of an offer from Company A, I have no problem reneging on Company B, or quitting Company B very early on. Company A would likely be offering much better working conditions and work-life balance, about 20% higher pay, and far better career prospects. I'm comfortable burning bridges with Company B, as I'd have no reason to return to them once working at Company A.
My question concerns the optics of my position when I go onsite with Company A. I expect interviewers to ask me questions that - answered truthfully - will reveal that I've quit my previous job, accepted an offer from Company B, accepted relocation assistance from Company B (which I'm happy to refund if I renege), and may potentially renege on Company B at short notice if the opportunity arises. I would never volunteer this information, but I do expect them to ask.
In short, how will this situation look to technical interviewers from Company A if presented truthfully and without significant twisting of words? Should I be concerned about it harming my chances of receiving an offer from Company A, or even burning bridges with Company A?