Configure nginx as a reverse proxy for dawarich. Alternatively you can configure a reverse-proxy of your choice to serve these paths:
/ -> ${pkgs.dawarich}/public
/ -> 127.0.0.1:{{ webPort }} (If there was no file in the directory above.)
Make sure that websockets are forwarded properly. You might want to set up caching of some requests. Take a look at dawarich's provided reverse proxy configurations at https://dawarich.app/docs/tutorials/reverse-proxy.