Cannot get SPA deep link to work with subdirectory redirect

Question

I am trying to set up a straight-forward scenario. We have a SPA (Angular) app that is built into a subfolder of our nginx container (e.g. /usr/share/nginx/html/foo). When navigating to https://example.com, I want to be redirected to https://example.com/foo. I tried the following config:

user nginx;

worker_processes 1;

events { worker_connections 1024; }

http {
    server {
        listen 80;
        root /usr/share/nginx/html;
        include /etc/nginx/mime.types;
        index index.html index.htm;

        location = / {
            rewrite "^$" /foo;
            # return 301 ...
        }

        location / {
            root /usr/share/nginx/html;
            try_files $uri $uri/ /index.html;
        }
    }
}

I have tried alternatives for the second location section, e.g.:

        location ~ ^/ui(.*) {
            root /usr/share/nginx/html;
            try_files $uri $uri/ /index.html;
        }

Redirect works, so https://example.com or https://example.com/foo works. But any deep link will not, e.g. https://example.com/foo/bar/baz. This will return 404 as it's likely not activating Angular.

As a side note, but perhaps important: this is hosted as a container within kubernetes, so I hope it's not the ingress that is blocking here.

With which configuration can I get the deep link to work as expected?