An update:
I noticed that the statics GET ignores the publicPath set on quasar.conf.js, so I tried:

include in quasar.conf.js assetPublicPath: '/node/' -> nothing on src-ssr/index.js:
2.1.app.use('js', express.static(path.join(__dirname, 'www/js'))) -> nothing
2.2.app.use('*/js', express.static(path.join(__dirname, 'www/js'))) -> nothing template.html: if I include <base href="/node/"/> on the header (based on this stackoverflow answer), the images are loaded but not js, css…

Probably this is simple and a newbie mistake, but thank you all for all the help you can give.