@wentasah My solution after same and / or similar problems:
use the following in my #configurationdotnix #nixconfiguration
configuration.nix
file:
services.printing.enable = true;
services.printing.drivers = [pkgs.brlaser];
with additionally the lines in the image below:
Complete configuration.nix is listed here
https://pastebin.com/SCNv2c3h
see lines 78-158
feedback welcome !!