If you physically rupture pollen grains, then, yes, there are human digestible nutrients inside. For example, extensive chewing, a blender, or some cooking methods can do this more or less efficiently. I'm not in any way recommending the stuff.
In fact, there are a lot of small insects and other arthropods that feed only on pollen. The whole topic of being hard/easy to digest is called bioavailability, which you can read about now that you have the search term. This is a really interesting topic, BTW. Bioavailability of some nutrients changes with ageing in humans. Old guys like me secrete less stomach acid than young people. A plant with tiny lithocysts of calcium, say eaten raw, provides less calcium per unit volume for old folks versus young folks. There is less acid in the gut to help break down the lithocysts. And there is a disparity between the amount of calcium required in the diet, versus what your body actually needs and uses. I'm too lazy to get a reference with good numbers, but, the recommended daily value for calcium in the US diet is greater than the calcium actively untilized - for all ages. Because of bioavailbility.
Pollen is remarkably resistant. Palynology is based on the fact that the enzymes to break down pollen walls are not ubiquitous in nature. For example, lake bottoms have lovely, pretty much yearly varves made of pollen and sediment. These persist for very long periods of time. Fossil pollen from them is very important for getting information on local climate at the time of the deposition of the pollen.
Pollen and spores (the forerunners of modern Angiosperm pollen) can be old, as in Silurian age. See the picture of Silurian plant spores (modern plants were not around then).
https://en.wikipedia.org/wiki/Palynology