Integrating french or other western missiles shouldnt present too much of a problem. I believe its comes down to the customer preference/requirements as to which avionics and munitions they want to have integrated into their vipers. I know Israeli vipers fly with Israeli hardware and missiles like the python 4/5.
In the past, numerous French missiles were tested on the F-16, including the AS-30 anti-ship missile and the R.550 AAM. Below you can see pictures of a Belgian AF F-16 carrying both missiles.
A Belgian F-16A carrying a AS-30L missile, with Sidewinders attached to the wingtips. Also note the laser designator pod attached to the right chin station. A Belgian F-16 was used in the early nineties to test the integration capabilities of the AS-30 missile. The F-16 was borrowed from the Belgian Air Force by SABCA and cleared of all markings for this purpose [SABCA photo]
Belgian F-16 without ID marks, used as a testbed . Seen here firing a Matra R.550 Magic II missile. The Belgian Air Force never adopted the missile for operational use [SABCA photo]
Although thoroughly tested and validated on the F-16, the were never fully adopted.