Gallery of the 3 levels => https://imgur.com/a/xPTralG
Edit:
I get it now. Triangles, Chevrons, and whatnot.
The sidebar is required to go to the side menu.
But I spend every day in Maps and it was never obvious to me.
I wanted to screen cap the year ago Maps api layer selector where it was Satellite and Map then with the Map option of terrain.
Edit Edit:
To modeless:
Click something in the sidebar... that revels another sidebar...
Back to UX how am I going to know that clicking "Globe" is a toggle state like a checkbox? (https://i.imgur.com/rvLdzM8.png)
I've been using Google Maps for years, I preach it. These things make me feel like a heathen.