I would prefer "advantage" or "benefit".
You can have synergies when the two companies are merging:
I don't see how it's applicable to market entry unless you are acquiring a local company.
It's applicable to talk about key capabilities that will allow you to win the market share
Synergies could be applicable if M&A is involved with the market entry strategy. Synergies can be realized with top-line (additional revenues) or bottom line (lower costs) growth. There are also negative synergies (i.e. additional investments required in marketing etc.) that one needs to think about as well.
Look at capabilities.
I agree with the other comment.
When looking at "synergies" for a market entry case, I would rather refer to this as the "current company capabilities". Here, you will be able to look into currently established distribution channels, cross-selling opportunities, connections/relationships, etc.
Naturally, I tend to connect the word "synergy" with M&A activity and you don't want to give the impression that you're mistaken on what the client is looking to do.
the definition of "synergy" will help you. A synergy takes place when the combined value and performance of two companies will be greater than the sum of the separate individual parts.
Depending on the market entry strategy, if it is rolled out by making mergers and acquisitions (e.g. Company X acquires local company Y to enter the ZZZ market), there could definetly be potential synergies to evaluate.
Hope that helps!