Depends on your field. For some fields (e.g., public health, social work), government (especially, federal) employment is probably highest the pay you could get and still affords a balanced lifestyle in most cases.
As the Shocking Simple Math (tm) tells us, though, FIRE is really about savings rate, so work-life balance seems like the key. If you're able to cook your meals, shop for deals, pursue hobbies, think about the future, havethe mental energy to optimize your lifestyle, you're well-positioned for Mustachianism. This is not true for all government jobs; the inverse is not true for all non-government jobs. But, it's probably more likely in government.