Can I use OpenBSD as a desktop system?
This question is often asked in exactly this manner -- with no explanation of what the asker means by "desktop". The only person who can answer that question is you, as it depends on what your needs and expectations are.
While OpenBSD has a great reputation as a "server" operating system, it can be and is used on the desktop. Many "desktop" applications are available through packages and ports. As with all operating system decisions, the question is: can it do the job you desire in the way you wish? You must answer this question for yourself.
It might be worth noting that a large amount of OpenBSD development is done on laptops.