In the already released second mha movie, Bakugo exhibits pain tolerance that outstrips anything Cap can hit him with, and is perfectly capable of moving and fighting. So no, his combat abilities will not be hampered from Cap's single hit.
Exactly what is this hit supposed to be doing to Bakugo anyway? If he hits Bakugo's arm or hand, Bakugo literally won't care, he'd have to hit a pretty critical part of Bakugo's anatomy to severely hamper his combat skills, which I doubt with Bakugo's pseudo flight, hit and run mobility.
Stun grenade is a literal free hit on Cap that will harm him as bad if not worse than Bakugo since it'll be a full body explosion 6x his durability. His shield is not going to protect him 100% as you seem to assume, there is only so much of a literal building sized explosio it can absorb for him.
Cap has never in his entire career come out unscathed from taking a head an explosion comparable to Bakugo's, even with his shield helping him. Name a building sized, high 8-c explosion Cap tanked through with minimal damage due to his shield alone. Bakugo doesn't need to be in a better condition to fire off his big explosions repeatedly, if anything, being heavily damaged incentivizes him to use his big explosions, like vs All Might.
How is Cap more aware of his margin of error than Bakugo? Neither of them know how strong the other is, nor what the other can do. Cap will protect himself against the standard explosions as best as he can, but he has no counter to stun grenade or the explosions that literally engulf the entire area he takes up. Bakugo can absolutely cover himself while injured, pressing on through pain is what he does, and he's shown that quite clearly. Hurting Bakugo just pisses him off and makes him shoot out stronger explosions even more.