what is the probability for a primary amine to form a nitroso group, is it active for such reaction?
Primary amines form instable diazonium ion, not nitrosamines.
Theoretically, the diazonium ion may alkylate the original (primary) amine to form a secondary amine and this one may form nitrosamines.
However this mechanism is quite improbable and requires an excess of nitrite.
An update on the current status and prospects of nitrosation pathways and possible root causes of nitrosamine formation in various pharmaceuticals
No it cannot form.
Primary amines react with nitrosating reagents to form short lived diazonium ions which further decomposes to give molecular nitrogen.
Primary amine unable to form nitrosamine but dueing manufacturing of Primary amine, if secondary or tertiary will be present as an impurity than chances are there. So better to review impurity profile of any primary amine molecule.