Getting PHP-FPM to work with nginx - a pretty common setup - involves unnecessarily much work. Much of this could be abstracted away by a module configuration option.
Copy-pastability of configuration examples is low, which can make it challenging to understand how to configure something correctly without making a mess of your existing configuration - because the same configuration can be represented in many ways and often examples are dependent on context and abstractions that live in other people’s repositories. Nix flakes would probably alleviate this a lot, by reducing the need to copy-paste examples, instead lowering the bar for publishing and consuming third-party abstractions/presets.