Answer and a question: strava heat maps (google that) provide relative exposure of bike riders and runners, although biased to that application brand. Does anyone know of similar service with a broader source data?
it depends on the country and the spatial scale. Actually there are a few available datasets out there- mostly for the US and a few other countries... have a look on http://www.quanturb.com/data.html and check carefully the census bureau for example. best.
There are many options, but you may want to try the following ones:
A Large-scale Traffic and Weather Events Dataset: https://smoosavi.org/datasets/lstw. This dataset offers information on 25 million traffic events (accident, congestion, road-hazard, etc.), over the United States from Aug 2016 through Dec 2019.
You might also want to check the following: https://smoosavi.org/datasets/dact . It offers information on 50 vehicle trajectories with GPS and OBD-II port data, 13 hours of driving by multiple drivers, and it is annotated by meaningful driving patterns (speed-up, turn, hard-brake, etc.)
Not sure if it matches your use-case, but you could try BestTime.app (https://besttime.app ). They provide foot-traffic data with week forecasts and live data for popular places like bar's, parks, restaurants, shopping (malls), gyms, retail, etc. Maybe you could derive when at what day and time (popular times) most people socialise in certain areas/ venues. They also provide some tools to visualise crowds on a heat map and narrow the data down with plenty of filters (day/time, foot-traffic intensity, ratings, etc).
GiS data sets depend on where. ERSI and Google own a bunch and you can get a decent car mounted or specified GPS Wayfinder much more precise than a phone but I'm told they scew the data constantly to not have an enemy use out GPS to guide rockets in our front doors..