This is how I set up a readonly OpenBSD 6.8 system.
The system is a router running off an SD card. I want to minimise wear on the SD card, and I want the system to come up clean after a power failure. For times when I need to make a quick tweak, I can still go read-write temporarily.
This is unfortunately not a supported OpenBSD setup, and small tweak to /etc/rc is necessary.

httpd is the OpenBSD built-in Webserver. It has support for FastCGI which is a protocol that allows Web servers to execute external programs through a FastCGI Server. In OpenBSD, the FastCGI Server is called slowcgi and also is in the default installation. So it is possible to build a dynamic website or API without installing additional packages.

In which the author babbles semi-coherently about a window manager for Unix-like operating systems.

capscreen is a shell script for screen recording on OpenBSD using ffmpeg(1).  It captures the screen and microphone, and optionally overlays a webcam video feed in the top-right corner.