POV cheating

I wouldn't call it cheating to drop into a character's POV who the reader has seen before. I think the Uncle Jim thread addresses this as one reason to have solid secondary characters. You can use them for POV characters at need. Just make sure the reader understands quickly whose eyes we're seeing through.

I personally would find it jarring...but I'm kind of a POV-control-freak myself. (I use TONS of different POVs in my stories, but I like to hope there's a sort of order to it...)

Would there be any way to insert smaller scenes somewhere earlier in the story, told from the POV of the non-POV characters you mention? This could establish that the story will occasionally be seen through their eyes. To just suddenly switch POV to a character whose mind has been closed off for the first 3/4 of a work is...well, jarring, for lack of a better word. Perhaps if their POV showed up sooner--even halfway through the book--it wouldn't be so sudden. But to switch to a non-POV character when the book is almost over seems almost like a writing device or contrivance of some sort.

Another option would be some sort of omniscient POV for the citywide scene, but again, IMO it would have to be established earlier in the work that this POV would be possible.

That's just my opinion though, obviously others won't necessarily agree.

As long as you use a line space as you would do for a change of scene, changing POV shouldn't be a prolem.

I'll answer this as a reader:

I love multi-POV stories. Perhaps I'm nosy, or I get bored of most MCs, but I like to see in other people's thoughts too.

I wouldn't even mind if the new POVs came near the end of the book so long as I know the characters beforehand. I think for the most part, we as writers know the POV laws and get irked because of this.

Multi POVs are just confusing to get into in the beginning of a book. But they're still an enjoyable read

I think as long as your POVs are clear (and not headhopping like crazy) it should be fine. Just because 3/4 of the novel is limited to one or two POVs doesn't mean it has to stay that way.

If it works...

I had a similar situation. In the middle of my story I wanted to suddenly show secondary characters' POV.
What I was wondering, whether in this case or between just two MC POVs, how short can each scene be? Can it make the reader dizzy to read two paragraphs of one POV then switch to another for another 2-3 paragraphs and then switch again?