Sure. Those are pretty good examples, too.
What I'm reading here is you making choices about scope and scale based on what elements of the fiction are important to you, adding details as they become important, without worrying about explicit "zooming in" or "zooming out" concerns. Which is fine! Especially if the game moves along well, since players have only limited opportunity to change scope and scale when they say what their characters do (compared to the MC).
Your description of a sniper here, and Balls there, and the probability of Dremmer over there, positions them all as separate elements, and more importantly, in different places. Whether or not you purposely intend for them to be dealt with separately, you're implying it, by giving them separate identities and spacing them out.
(Whereas, how did he get to the house? "I drive to the other side of the ridge, park the van, and sneak up to the house"? And the response is "okay, when you get there..."? So there you are, zooming in, increasing the detail. You get the idea.)
And maybe Fido's player takes that cue and deals with each in turn, and maybe you get even more into details, and it's a drag out, knock down fight that requires half a dozen moves in total before he gets into the house and finds Millions and Joe's Girl.
Or maybe Fido's player uses the autofire tag to shoot all of them at once, instead of dealing with each dude individually, as is suggested by their spacing and distance. If he's really charging the house, riddling it and everyone he can see full of bullets, I could just say the sniper fire and Balls' retaliation are what make it seizing by force. Maybe it's a 7-9 result, and he picks terrible harm and take definite hold. Wilson and Balls are taking 4-harm minus armour and maybe cover worth 1-armour for the wooden walls (or maybe it's a cement building? better cover, bullets don't blow through the walls?). So they both die. Maybe Dremmer gets hit too, maybe from bullets going through the wall, maybe not. Fido takes 3-harm each from the sniper rifle and the AK, so after his 2-armour he takes 2-harm total. And he seizes the tactical position that is the front of the house, probably Balls' doorway. So even if Dremmer didn't get hit, he can't just ambush Fido out of nowhere, 'cause he's got this position staked out.
Bam, even if he hasn't seized the house in it's entirity, all that's left is Dremmer and maybe a wounded Wilson if he's got some concrete walls to protect him. Of course, if the walls are wooden, Fido's probably gone and killed Millions and Joe's Girl as well, so he maybe shoulda thought about this first. Or maybe he did think about it, and he's deliberately trying to maximize his resources rules-wise and his narration stems from that.
To me, this looks like it addresses all the elements in your example, except perhaps Fido's intentions regarding Millions and Joe's Girl, the ambiguity of Dremmer's location, and the structural composition of the house. And it looks like it has the possibility of resolving the whole fight in one roll (though not the certainty).
Regardless, it would be at this point where you as MC make that decision, and decide what happens next. Do you decide they all three die or flee and wrap it up? Do you decide that Dremmer is still a concern and Fido's gonna have to act under fire to get his pistol out in time to shoot back? You can decide based on your perspective on the fiction, based on whether or not you personally want to see some more fighting, based on time real-world time constraints or on how the spotlight time has been distributed so far -- but you're still deciding based on what you think is important, and the granularity of your description is going to reflect that.
Now, granted, it's not like there are jarring differences in scope+scale here due to zooming or anything. And this comes from following the fiction and describing actions in a way that makes sense (and there is definitely an art to being a player and selling certain things to a GM/MC). Especially since the original scope+scale in your example is mostly implied.
But given that these are really all just decisions you make while playing the game, if you've accidentally set yourself up in a position where those six guys on the way to something important aren't actually important, and are just there because you were describing a bunch of shit at some point, you can absolutely just decide, regardless of the granularity of the fiction leading up to it, to resolve the whole thing, all six fights if that's what the fiction is asking for, in one roll. I mean, the whole reason you are doing what the fiction demands at all is to present a coherent setting to the players, so if the player in that case is all cool with it, then you're a-ok.
(And if players are NOT a-ok with the MC's changes in scope+scale and your zooming in and out, I've been that MC too but I wrote about it already.)