[snthd]

RDS-TMC transmits traffic data over FM radio. https://en.wikipedia.org/wiki/Traffic_message_channel Some is encrypted, some not.

It might be possible to model traffic with OSMnx to assign weights to roads by expected traffic levels https://github.com/gboeing/osmnx

Depending on where you live you might be able to get traffic data and maybe traffic models from public authorities using Freedom of Information requests. eg London's TFL:

https://datatonic.com/case-studies/traffic-prediction-tfl/

>Designed to gather data from all over London, TFL’s Urban Traffic Control (UTC) system collects car activity records via 14,000 individual road sensors located throughout the city. We were given 3-months worth of these records to create our traffic prediction model — totalling over 120 billion data points.

Once you have road weights you can use something like brouter - https://brouter.de - it can already do road types and elevation.