Tips and advice for repairing front yard stairs cheaply?
I am not a mason, but my guess is this will be difficult to do it well. My advice is even more suspect since I cannot see the stairs themselves and the extent of the problem.

A thin veneer over some faces and a thick one in other places will chip and crack, especially if water ever gets in and freezes. But the major problem is the existing cracks. Those cracks may come from settling/frost heaves, etc. That will leave this new layer prone to the same problem. In order to prevent this, the new layer would need to be reinforced to strengthen it, and it would need to be thick enough to be able to resist cracking when one half of the stairs tries to move.

Do these stairs rest on bare ground? Or do they have a proper foundation underneath to avoid frost heaves? My guess is the cracking suggests they are moving around with the weather.

A poor fix that fails in a couple of years is worse than doing it right the first time.

The best solution probably is to remove them and put new stairs in.