Can I frost the bottom part of the street-side window?

I think that's a great idea. If you don't want the permanence of a spray on frosted glass, you could look into window films that will provide the same effect but will be easier to remove down the road.

What about using Bubble Wrap ???

This looks interesting, Please conider checking the q&a and reviews to see if it might interest for you privacy frosting needs.

https://www.amazon.com/Rust-Oleum-1903830-Frosted-Glass-11-Ounce/dp/B0009XCKBA

There are plastic applications to put on windows that LOOK like frosted glass. They are great for privacy. Ask for them at your local home improvement store. They are commonly used in our country.

Spray paint at Home Depot...

https://www.homedepot.com/p/Rust-Oleum-Specialty-11-oz-Frosted-Glass-Spray-Paint-1903830/100195608

Stores like Lowes have plastic window covers that come in a roll. There are lots of different patterns you can buy, in my bathroom it's bamboo. I don't know why builders put windows in showers! You can also use a spray on coating that will frost the window, although if it gets wet, it goes transparent. My second bathroom has this sprayed on the outside of the interior window between the storm window and the interior window. Works just fine. Both let light through but give you privacy.

Thank you very much! I was afraid to try but I will go check out different patterns!

I did it and it looks great! And it was EASY! The only warning I have is that when I squeegeed the air bubbles out I failed to go outside and check. Fortunately the tiny air bubbles I missed don’t show much. Now my next window will be perfect!