Dutch (and Dutch-bound) rail network overview: https://treinposities.nl/ And the equivalent for buses: https://busposities.nl/ Not all of them have GPS trackers, so some positions are guessed.

There's functionality for this in the official Dutch Railways app, but it looks like they didn't bother putting that onto their website. There is a common source of open data for most of these details, but I don't find the docs to be very complete.

Wow! https://treinposities.nl/ even shows historical positions since 2019. Feels like something you'd only see in a cheesy murder mystery.