Should i upgrade to LAUNCH plan for Appflow

Im really interested in deploying my app through AppFlow and want to upgrade to LAUNCH plan. My app will be only used in my country (Serbia) and i will host my backend portion of my app on other hosting.
My question is :
-Is it better for me to host both apps on hosting from my country>
-If i use appflow and host backend in my country will it impact performace of app?
-Can i host both backend and frontend protion on AppFlow and will performance be worse than if i would host both backend and frontend on hosting in my country?

Thanks ,any suggestion and answer is appreciated. Im really considering upgrading but i want to know all the facts and get best performance for app users.
BTW app will have a lot of API calls to backend