They are chickens. With any breed or mix, they might be fertile they might not. Rangers are no different.
The general recommendation is to not hatch pullet eggs. I'll mention a few reasons. For an egg to hatch pretty much everything has to be put together right. The internal egg making factory is pretty complicated, pullets sometimes have problems getting everything right when they start laying. That's why some pullets' first eggs can be so weird. No yolk, double yolk, thin or soft shelled, really thick shells, or just funny looking. Not all pullet eggs are weird, but they are common. Some of the stuff that has t be right to hatch is stuff you cannot see with your naked eye. Not all pullet eggs are like this, to me it's surprising how many get it right. Most seem to.
The first eggs a pullet lays are typically really small. That's natures way to protect a partially grown pullet from damaging herself by laying really large eggs. Those tiny eggs do not have enough nutrients or size for a chick to grow very big before hatch. The chicks that hatch will be small. I don't know if they will always be small or if they catch up in size as they grow, they have the same genetics as chicks from larger eggs.
I hatch pullet eggs. You can get some to hatch. My hatch rate with pullet eggs is not as good as with larger eggs but some will hatch. Sometimes a lot of them will hatch, sometimes not a lot.
When I hatch chicks I seldom lose one. Anybody that hatches and raised a lot of chicks know they will sometimes lose one. When I do it's often one that hatched from a small pullet egg. That may be because they're not as strong as chicks hatched from larger eggs but I'm not sure. They are usually pretty active. I suspect it's more likely a birth defect because maybe the egg wasn't perfect after all. But I don't know.
For whatever reasons my hatch rates and survival rates aren't quite as good as from larger eggs. I find if the pullet has been laying about a month these rates improve.
A story. One time when I was collecting eggs for the incubator I had two pullets laying so I threw their eggs in with the others. I could tell which pullet laid which egg by shell color. Out of 5 eggs laid by one pullet I got 5 chicks. They all did well. Out of the 6 eggs from the other pullet I got 0 chicks. None even started to develop. I suspect she wasn't squatting for the rooster and he didn't bother to chase her down but that's a guess. I don't really know.
Mine were dual purpose chickens, not Rangers. But I don't know why it would be any different with them, they are just chickens. I don't now what you have to lose by trying it. If you do, let us know how it goes.