What are the legitimate excuses that permit a worshiper to delay their prayer and not perform it in congregation, especially if they work in a government sector that does not enable them to pray on time?

Delaying the prayer until its time expires is impermissible, except for one who is asleep, or forgetful, or intends to combine prayers due to an excuse. As for delaying it from the beginning of its time while still performing it within its prescribed time, there is no harm in that, though it is preferable to pray at the beginning of the time. As for congregational prayer, it should not be abandoned except for an excuse such as illness or fear. If the workplace does not permit congregational prayer for a reason that necessitates it, such as guarding, then one should pray alone within the time.