The four-time African champions face El Tri at Houston's NRG Stadium in Texas, USA, on June 28, three days before locking horns with the Stars and Stripes at the Pratt & Whitney Stadium in East Hartford, Connecticut.
The two games will, however, be preceded by a 2019 Africa Cup of Nations qualifier against Ethiopia on June 11.
"Friendly matches are always good opportunities to see as many players as possible [and] also [assess] the strength of a team, so for us, those games in the USA will serve a useful purpose," Appiah told KweseESPN.
"The idea is to win every game and build on a team that will grow from strength to strength.
"Everything else will be secondary."
Ghana are looking to pick up the pieces after recent disappointments.
The Black Stars are on the verge of missing out on qualification to the 2018 World Cup following a poor start to the third round qualifying campaign.
Ghana's campaign at the recent Africa Cup of Nations was equally disappointing, having crushed out in the semi-finals.
Appiah has since May been reappointed as coach, taking over from Avram Grant, after earlier guiding the Black Stars between 2012 and 2014.