Is it permissible to wear the niqab while fearing that it might affect the workflow in the pharmacy and lead to a decrease in business?

For a woman to cover her face is an obligation, and it is a fard (religious duty) upon a Muslim woman. Obedience brings sustenance, not the other way around. Allah Almighty says: "And whoever fears Allah - He will make for him a way out And will provide for him from where he does not expect."