NodeJS Express Angular serving a login page entirely separate from the SPA - node.js

Question

I am building a SPA in Angular 8. I have a multi-stage Docker image that runs ng build to build the distribution and then a simple express server is used to serve the application. (Note: The backend API is on an entirely separate express server.)
Requirements
I need to setup a login page "outside" of the SPA. The login page must be displayed if the user is not authenticated, that way the SPA is not bootstrapped until the authentication is successful (by checking a bearer token in the authorization header).
Questions
Do I need a separate Angular installation to load the login page separate from the rest of the app? Or, should I just skip Angular for the login page and build a simple express page with Pug that sends a POST to the API for authentication?
Note: I am seeking general advice on how to proceed and any examples would be very helpful as well.
Dockerfile
### Dev, QA, and Production Docker servers ###
### Stage 1: Build ###
# Base image
FROM node:12 as builder
# Set working directory
RUN mkdir -p /home/angular/app
WORKDIR /home/angular/app
# Add `/home/angular/app/node_modules/.bin` to $PATH
ENV PATH /home/angular/app/node_modules/.bin:$PATH
# Install and cache app dependencies
COPY angular/package.json /home/angular/app/package.json
RUN npm install -g #angular/cli#8 \
&& npm install
# Add app
COPY ./angular /home/angular/app
# Generate build
RUN ng build --output-path=dist
### Stage 2: Server ###
FROM node:12
USER node
# Create working directory
RUN mkdir /home/node/app
## From 'builder' stage copy over the artifacts in dist folder
COPY --from=builder --chown=node /home/angular/app/dist /home/node/app/dist
# Copy Express server code to container
COPY --chown=node ./express /home/node/app
WORKDIR /home/node/app
RUN npm install
# Expose ports
EXPOSE 4201
CMD ["npm", "start"]
Express server for Angular SPA
This server is run when the Dockerfile executes its command CMD ["npm", "start"]
const express = require('express');
const http = require('http');
const app = express();
// Set name of directory where angular distribution files are stored
const dist = 'dist';
// Set port
const port = process.env.PORT || 4201;
// Serve static assets
app.get('*.*', express.static(dist, { maxAge: '1y' }));
// Serve application paths
app.all('*', function (req, res) {
res.status(200).sendFile(`/`, { root: dist });
});
// Create server to listen for connections
const server = http.createServer(app);
server.listen(port, () => console.log("Node Express server for " + app.name + " listening on port " + port));

Answer 1

Angular supports multiple applications under same project. You can create separate login application using following command:
ng generate application <you-login-app-name-here>
This way you can keep only login related code in '' and other code in you main app. You can build, test or run this new app separate using following commands:
ng build <you-login-app-name-here>
ng test <you-login-app-name-here>
ng serve <you-login-app-name-here>
Angular will generate the build output in /dist/ folder which can be mapped to express route to serve file.