What did Iowa do scheme wise that helped the OL out at all under Brian?
Depends which season/game you are talking about. But overall, I don't have the necessary inside information to answer that question very well.
What I can tell you is the offense was never broken until the O-line was broken.
Things started to surface in the 2nd half of the '21 season for the O-line. It was compounded by an RB that decided to save his hits for the NFL, rather than fight for the tough yards, but that's another story.
Then in '22 the O-line was completely raw, underdeveloped in every way, and broken. This was compounded by an immobile QB, but the offense was broken regardless.
'23 showed some improvement from the O-line, as they had more strength and experience under their belt. And to at least somewhat answer your question, Iowa adjusted to much more pin-and-pull blocking scheme, which I would assume BF had a hand in. But mostly due to an emergency QB having to play most of the season, the offense was not able to take off.
This season the O-line is a semi-finalist for the Joe Moore award, and Iowa's offense has drastically improved. Again, from my under informed position, it seems that Lester has brought some helpful scheme. But KF, and guys like myself said even before Lester that the O-line and offense would be significantly better this season. Why wouldn't it be?
There is no point in blaming BF for anything, as that ultimately fell on KF, and to credit TL is also to credit KF