No

The current FOSS offerings do the calculations on your device, so you'd need the maps downloaded locally. The small apps that stream their tiles from OSM/Jawg/ESRI/Mapbox etc. don't support navigation because of this

Not FOSS but the closest thing you'll get to this is GMaps WV on F-Droid, made by the DivestOS team. Even that does not support navigation though, it only provides directions (usable for me, your mileage may vary...)

Not under 50MB but there is: https://organicmaps.app/

And

https://osmand.net/

I find Organic Maps best for driving and OSMAnd+ best for walks.

I like organic maps cause it does shit locally, offline. It has to download the maps though which is certain to be larger than 50mb. What you are looking for is a cloud based maps solution like google maps and you aren't going to find that in foss space

I don't know the size, but Organic Maps may be rather small

Not foss but magic earth is a great app that does not rely on google maps. It can also work as a dashcam.

Gmaps WV on F-Droid?

Under 50mb is a very hard ask. Maps have a lot of data.

Looking for the same thing for Linux fwiw, with live turn by turn navigation and GPS support.