I asked in the old forums if anyone had installed semaphore from pkg on CORE.
It is possible.
Install from pkg, then download and extract the release for FreeBSD on their GitHub page, replace the current one in /usr/local/bin with the downloaded one, then run semaphore setup to set up your server.
The rc script will also need to be modified with where ever your config file is, etc…
But after that, the binary will run and the webserver will be up.