Probably any citrus, like orange, grapefruit, lime, etc., can be substituted for lemon juice/zest.
Many times lemon juice and zest are used in recipes just to flavor the dish and can be left out completely.
Sometimes, though, in a bread/dough recipe that calls for baking soda, which is a leavening agent, the acid in the lemon juice may be needed to activate the baking soda so the dough will rise, if there is not another acidic such as buttermilk, yogurt, honey, etc.
In dough recipes where an acidic liquid like lemon juice is not required to activate baking soda, the liquid my be needed to obtain the correct consistency, so if you omit the lemon juice, replace it with another liquid like water or milk, if needed.