Besides as casual shirts, I make linen as dress shirts also. As a matter of fact, the most formal of shirts I make is from a very rare type of linen. Linen is available in many, many textures, weights, weaves, and stiffnesses. The one we commonly use for casual shirts is known as "handkerchief linen" and is just about as soft as linen gets. This is what it looks like:
On the other end of the shirt linen spectrum, is a rare, semi-stiff linen available in white only with a finish one could only term as "shiny". This is the linen which, with the addition of seven tons of starch, is used for making 'antique' detachable collars. Without the starch, it makes one of the most beautiful dress shirts I have ever seen. Regretfully, I have no photos of it at the present time. If you have a choice on your pure linen fabrics, try to get one woven in Ireland rather than Belgium of Chechoslovakia. Then, of course, there are the linen & cotton blends ... but that's a story for another day.