The MTA has a Mobile Sales vehicle program that travels to various NYC neighborhoods offering services such as:

As far as I’m aware, the MTA Mobile Sales service has not come to Roosevelt Island.
I asked Roosevelt Island’s NY State Assembly Member Rebecca Seawright if she could help get the MTA to bring a mobile sales vehicle to Roosevelt Island.
Today, Ms Seawright shares this letter she sent to Senior Vice President Department of Buses/MTA Bus Company Frank Annicaro.

Dear Vice President Annicaro:

Thank you very much for your leadership at the MTA.

On behalf of my constituents on Roosevelt Island, I am writing you today
to request that a mobile sales vehicle return to the Island.

As you know, Roosevelt Islands over twelve thousand residents have
limited public transportation options. The Trams recent, well-chronicled
overcrowding has only intensified these challenges.

Over twenty percent of residents are older New Yorkers and thousands are
people with disabilities. Both groups are eligible for reduced fare
and would benefit from the mobile sales vehicle. As Chair of the
Assemblys Aging Committee, I request the return of the Roosevelt Island
mobile sales service providing access to reduced fare applications, OMNY
guidance and other customer services, that would otherwise be inaccessible
to older people and people with disabilities.

I remain thankful to your department for providing these vehicles to my
district on the Upper East Side. I have witnessed firsthand the benefits
they provide, especially during the current MetroCard-to-OMNY transition.

Thank you for your consideration. I appreciate your attention to this
important matter of accessibility. If we may provide additional
information, please do not hesitate to contact my Chief of Staff, Courtney
Ferrissey, at 212-288-4607.

Sincerely,

Rebecca A. Seawright, New York State Assembly Member

Here’s Assembly Member Seawright as Chair of the Committee on Aging,
speaking with the New York State Office for the Aging’s Acting Director,
Greg Olsen, during a February 25 joint budget hearing on Human
Services.