I offer Nix office hours, either scheduled individually or a best-effort on Fridays. (General Nix Office Hours)
There are also Nix consultancies, if you’d like to pay for help.
Lastly, the time and effort of all the contributors and volunteers is their own. Donations to NixOS Foundation (or some of the the other initiatives that have been announced, eg. for better Darwin support) would be appreciated, or you can convince the organizations and companies you are involved with to provide more substantial support along the lines of what you suggest.