1- You need a Google account. 2 - The UX is not as good as Termius. 3 - The UI looks like garbage, but does it's job. 4 - You need to selfhost a server.
On Android, I use OSMAnd if I want to use a map and the openstreetmap.org web app if just quickly checking a distance, because OSMand can be quite bulky and my phone quite slow.
For public transportation (in Germany) I have Öffi.