How to deploy a polymer 3.0 build on NGINX (Raspberry Pi) - nginx

Question

How can I configure the Polymer build so I can deploy my app built on Windows to my Raspberry Pi running NGINX (in a sub directory)?
I could not install polymer-cli directly on my Raspberry Pi since the chromedriver (which polymer-cli needs) is only available for 64 bit Linux and the official Raspian OS is currently 32 bit only.
So I installed polymer-cli on my Windows machine, and created my first Polymer app according to https://www.polymer-project.org/3.0/start/toolbox/set-up, I also created the new-view page.
I can now run the app using polymer serve (which shows the app correctly in the browser on the Windows machine) and build using polymer build. Now I want to deploy so I copied the build directory (which contains three built variants, es5-bundled, es6-bundled and esm-bundled) to a sub-directory of the NGINX root, /var/www/html/polymer/build.
Firing up my browser and pointing at http://<raspberrypi-ip>/polymer/build/esm-build I see two errors.
The src="node_modules/#webcomponents/webcomponentsjs/webcomponents-loader.js" and src="src/my-app.js" in index.html gives 404. I could not find how to configure polymer-cli to change these, and still serve a working app in Windows so I manually added polymer/default/ to those two paths in the index.html.
Now I end up with a grey page in my browser, no further error messages...
Moving to my phones browser and entering the same url, http://<raspberrypi-ip>/polymer/esm-build, I actually see my app, together with an Oops you hit a 404. Head back to home link. following that link I get to my app, which seems to be working - but the URL is now http://<raspberrypi-ip>/new-view.
I've also played with the NGINX try_fileswithout luck...
server {
...
location /polymer/default {
try_files $uri /polymer/default/index.html =404;
}
}
EDIT: In Serving Polymer App to a /path not at root I found out that I also need to adjust rootPath in index.html. However I still get the 404 described above if I point my browser at http://<raspberrypi-ip>/polymer/esm-build/index.html...
Also, is there any way to refer to the rootPath in the <script src="">tag I manually edited above?
This is my first encounter with Polymer and NGINX, so any pointers are appreciated.