Is this synonymous with "What would Megan like?", e.g., if you were planning a family dinner or making a supposition?
No, that 'would' would need a conditional tense:
- Beth hoffai Megan?
- Beth basai/byddai Megan yn (ei) hoffi?
I would have thought that would and will both express the idea of wondering what Megan is most likely to want.