How can I enable gzip text compression in universal angular and nginx?

The gzip has nothing to do with Angular, it's a server thing. In nginx you can enable it by setting gzip on;

Like below:

server {
    gzip on;
    gzip_types      text/plain application/xml;
    gzip_proxied    no-cache no-store private expired auth;
    gzip_min_length 1000;
    ...
}

See the article below for more details:

https://docs.nginx.com/nginx/admin-guide/web-server/compression/

First step is edit nginx.conf file, that could be located /etc/nginx/nginx.conf or /usr/local/nginx/conf/nginx.conf, in most distributions.

Open nginx.conf file with your favorite editor. You can see that there’s already a block of settings regarding Gzip; you could always just modify those and un-comment out the lines as shown below :

# enable gzip compression

# Turns on/off the gzip compression.
gzip on;

# Compression level (1-9).
# 5 is a perfect compromise between size and cpu usage, offering about
# 75% reduction for most ascii files (almost identical to level 9).
gzip_comp_level    5;

# The minimum size file to compress the files.
gzip_min_length  1100;

# Set the buffer size of gzip, 4 32k is good enough for almost everybody.
gzip_buffers  4 32k;

# Compress data even for clients that are connecting to us via proxies,
# identified by the "Via" header (required for CloudFront).
gzip_proxied       any;

# This directive let you specify which file types should be compressed, in this case plain text, js files, xml and #css.
gzip_types    text/plain application/x-javascript text/xml text/css;

# Enables response header of “Vary: Accept-Encoding
gzip_vary on;

# end gzip configuration

Once your done with above config changes, restart or reload your server and you will now be serving site assets with gzip compression.

/etc/init.d/nginx reload

or

sudo service nginx restart