Is it permissible to travel on a work visa to serve pilgrims with the intention of performing the Hajj obligation, without actually undertaking the work?

It is not permissible to request a Hajj visa by claiming to be a worker serving pilgrims when you are not, because that involves lying and deception. However, if you obtain the visa in exchange for serving pilgrims, then you must fulfill that obligation, for the Prophet, peace and blessings be upon him, said: "Muslims are bound by their conditions, unless it is a condition that forbids what is lawful or permits what is unlawful."