I don’t think so, since he is the one tasked with putting the stones back where they go. Him doing anything else besides being the person Carter married seems to be something that would impact the time line and simply create paradoxs. It also seems clear to me that Rogers was always the person Peggy married—if I read that right. I might be mistaken but it seems, to me, that they always kept who Carter married under wraps for this particular reason. It isn’t so much Steve creating an alternate timeline as much as fulfilling the time loop that this adventure created. As it was always a part of the timeline, in this current iteration, that these events transpired (taking the stones and then promptly returning them).
As for Captain America on the broader scale, I think it was a smart move on Marvel’s part to put the character in the toy box for now. Frankly, it allows for Steve’s story to end but, should Marvel want to use him again, they can pluck him out of time and place him in the future again. Heck, with the time paradoxes showing up, I wouldn’t be surprised if we see Kang the Conqueror show up in the next Avengers movie.