You could generate an empty workspace like
$ npx create-nx-workspace expresswrkspace
and choose "empty" when being asked for a preset.
Then add node support with
$ npm i @nrwl/node
and generate a new empty node app like
$ nx g @nrwl/node:app myapp
From there you can add express etc.
nx g @nrwl/node:app myApp framework=express directory=backend js=true --verbose
possible options: https://nx.dev/packages/node/generators/application#options