FreeBSD is a great option on the server as well. Simple, stable, mature, and great documentation.
It's theoretically possible to use it in prod; I know that some companies (Netflix?) do it. But it's certainly not common and takes a lot of engineering resources to make it work.
Any competent Linux sysadmin could learn to admin a BSD in no time. The FreeBSD handbook and the man pages are excellent. In my opinion they are far better quality than their Linux equivalents.
You also won't have any issues if your server runs on an open source stack such as Python, PHP, Perl, Ruby, Java (OpenJDK), NodeJS, etc.
You're absolutely right about FreeBSD not having first party commercial support. If you need that, you're basically stuck with RHEL, SUSE, Ubuntu, or Oracle.
Many of the things I did as a traditional university sysadmin long ago probably works on FreeBSD, and if you wanted to deploy a LAMP (FAMP?)/Django/Ruby on Rails/etc stack it would probably be good enough, but the world has moved on since then. Once you want k8s, ansible, distributed filesystems, HPC, scientific, etc. it starts to break down really quickly. Many of the things I listed above may work, but it's the less documented, less supported, more annoying, and more likely to break path. The extra time spent getting it to work on FreeBSD and maintaining it is not time well spent unless there's a very specific reason FreeBSD is better, just grab RHEL/SLES/Ubuntu and skip all the hassle.
FreeBSD has its place in very limited scenarios and where you have the engineering resources to deploy it, but it should not be the default choice for a production deployment.