Prometheus might do some damage if he gets a free shot and stop a Snakeman barrage.
Still, did Kaidou's Boro Breath stop Luffy from wailing on him?
I see relative scenarios happening in 1041-1042. Luffy depends on his Gear 4
hoping he is able to accumulate enough damage in KO'ing Bigger Mom. With Big Mom having to play more defensively since she'll lack the speed to avoid his attacks and finding openings to countermove with her homies support.
Luffy will need to switch to Boundman to bounce away getting cooked inside Entei. Luffy charging in with Boundman will opt her prepare make a maser sword. Which will be missing but a she could exchange a blow with her canon while Luffy hits her with OKG.
With her having Misery being her next attack. Eventually Luffy will be on lose lose situation by either getting gassed out, internal wounds from maser blow exchange, or using his last strength to block even hotter flames of Misery until time.
Two points
Why are we pretending like Luffy found the solution to Kaidou's flames and Flame Bagua after Gear 5?
He had the solution all along. He just needed Gear 5 to beat Flame Bagua's size, power & volume.
Misery is clearly not on Flame Bagua's level to require Bajrung Gun.
Misery can be at the level needed for the story (as we outright saw Prometheus superior feats it did in WCI compare to Wano). Without plot conditions we know the facts in her homie feats:
1. Homies can sync with Big Mom
2. Prometheus has the ability to expand the range and size of his body (at the cost of losing speed per size increase as per canon)
3. Misery property implications of being same heat temperature as Flame Bagua/Karyudon.
4. Misery implies to copy both Prometheus and Hera abilities since they're just a fusion of each other.
And secondly, it's ridiculous to assume that Luffy cannot replicate PW/Damned Punk tiers of damage.
Especially with attacks like CoC-amped KKG or Kong Gatling.
For instance, both Big Mom & Kidd were visibly impressed at how much raw power that ACoA Kong Gatling carried, now imagine that with CoC....
Luffy might be restricted by timelimit, but with G4 & CoC, he atleast has a 50/50 shot at beating Big Mom.
It's quite the oppose to think Luffy can replicate PW/Damned damage when the closet ability we saw that matched it (and is clearly superior to due to CoC) was Bajrung Gun.
2. Its either disingenuous point or a misreading of the text to imply that acoa hype should grant because of BM impression towards it. When the hype was outright in concession by chapter 1008 CLEARLY.
So no, there was a reason Oda wanted to narratively have BM have a relative defeat as it was for Kaido. BJ output was the answer that put Kaido in the same position as BigMom. The same Big Mom that had to tank PW (w/ Kidd's moves), and a finisher of another Island busting nuke to equal what BJ did to Kaido.