Do alkylhydroxylamines form N-nitrosamines?
Yes they can in acidic solutions according to the abstract of this paper$^{[1]}$:


  O-Alkylhydroxylamines react with nitrous acid with a rate law $v = k_2\ce{[R^1NH2^+OR^2][HNO2]}$; the mechanism involves electrophilic nitrosation at the nitrogen atom of the free base. At acid concentrations below $\pu{2M}$-per-chloric acid, hydroxylamine and N-methylhydroxylamine react with nitrous acid by an acid-catalysed mechanism with a rate law $v = k_3\ce{[RNH2^+OH][HNO2]}h_\circ$; this involves initial nitrosation at the oxygen atom of the conjugate acid, followed by migration of the nitrosonium ion to the nitrogen. At higher acidities the O-nitrosation can be reversed, and the migration of the nitrosonium ion becomes the rate-determining stage.


Reference


T. D. B. Morgan, G. Stedman, M. N. Hughes, "Kinetics and mechanism of the reaction between nitrous acid and hydroxylamine," J. Chem. Soc. B 1968, 344-349 (DOI: https://doi.org/10.1039/J29680000344).