If anyone needs a Hugo module that can display multiple GPX files on a website, I’ve published the module I built for my own site on GitHub.
Repository: https://github.com/ravelzh/hugo-gpx-module
Demo page: https://go-offroad.ch/en/posts/jtte-tag-138-157-makedonien-bulgarien-go-offroad/#tracks
Regrads,
ravelzh