There have been a few attempts to create “docker type” files for LXD. The latest attempt being lxdops but this hasn’t got much traction based on the forums.
The quickest and easiest way to have a docker like experience would be to build and distribute images. But distributing images cost money. You have to build, store, & serve images for each architecture which adds up quick.
The next obvious solution is to distribute “text files” (json, yaml, custom-format) that set’s up containers & instances. This comes with its own set of problems, namely volume configuration when it comes to updates as we cant just blow away the whole machine. Any software that solved this problem would in essence be competing with SNAP and so is unlikely to gain any traction as canonical are unlikely push it.
The LXD crowd is normally quite technically minded and cloud-init is whats usually employed to solve the problems you are having with quick setups. But cloud-init is normally always custom and people dont need a “base image” (beyond an OS) that builds nginx / apache for them because its as simple as adding 1 line to a cloud-init.yaml.
It might be worth expressing problems you are having (“Is there a template for XYZ program”) vs general complaints as people cant build software around “it doesn’t fit a use case / onboarding problem i’m not explaining”.