PSA: None of the vaccines have been FDA approved. The EUA for each vaccine says that the FDA believes it to be safe and effective based on preliminary trials, but also warns that there is no FDA approved vaccine to prevent COVID-19. The vaccines haven't passed normal rigor, and they won't for about two years.
Though I think it's unlikely that an employer would require employees to take an experimental vaccine, I have personally decided to trust the FDA approval process on this. I'm saying no-thanks to anything merely emergency authorized unless risk factors worsen significantly.