I’ve spent several weeks at a time in the southern Alps, usually mid Jan to mid march. There has always been opportunity to ride, on road and some off, especially in the queyras.
Big dumps get cleared off pretty quick from the roads but be very wary of shaded corners
South facing sides of valleys also had glorious clear balcons which are joyful in winter sun and dry surfaces
Watch out for pine processionary caterpillars crawling along trails in big groups. I’ve seen loads on trails, they would really spoil your day if one flicked up in your face!