It might well be very difficult to help the Basques. It is very unlikely that either France or Spain will ever allow them to have their own independent country. It is also not clear that these two countries would respond to pressure from outside countries.
It is possible that the Basques might be helped in two ways. One way would be for outside groups to help the Basques create more of an infrastructure for their ethnic group. For example, they might help Basques to set up Basque-language schools in France where the language is not used in public schools the way that it now is in Spain. They could do so while encouraging the Basques to moderate their demands and work with national governments. This support could come from the Basque diaspora, particularly in the Americas.
Second, outside groups and even countries could try to put pressure on the French and Spanish to provide more autonomy. The Catholic Church might try to set up Basque-language parochial schools. Such pressures on the governments would have to be subtle, though, because it would otherwise be likely to antagonize the French and Spanish governments.