Yep, understood and agreed from the tech side. No need to place consistent elements over all icons into the files.
Still, if a background is planned, the size of the icons depends on the spacing. line thickness depends on readability which depends on the Background shape and transparency.
For the mockups i would advise to already at least plan with some kind of background.
The circles are just the most obvious design transfer from the "center" button which i really like in its simplicity.

I kind of picked this rim type because it looks like a steering wheel a bit. But yeah, makes no sense to put two references in one picture when others see an unfitting third one

Kind of close IMO. Only, do pedestrians or bikes go in the middle of a street?

And the arrow struck me. We kind of have our own universal navigation pointer already. Why not employ it here and give some consistency and identity? For example: