What is on the opposite wall?

" Ideas to fix it without pulling the whole thing out? "

None.

" Or ideas to fix it if we pull the whole thing out? "

Wall brackets as well as moving the entire newel post.

Thanks everyone. Who can help to fix it to move the post and install brackets? Do I find a carpenter or contact a company that only does banisters? It’s an old house so i would like to retain the style if I can.

That detail is original. I'd think long and hard before messing with it.

The fix is what Hallett&Co gave you.

Rather than move the newel post I'd replace the handrail with one like in this photo (with a smaller "jog").

I wouldn't want to hack apart that original old wood. Can you not add a more functional railing on the opposite side of the staircase?

Current advisors have given reasonable fixes.
It would take some ingenious engineering to adapt the right side banister for a hand hold.
A bit outre,but have you considered attaching a suitable brass rail to the old banister?
You could also attach rope as a handhold.
Think way outside the box!
A ship wright may be the best person to consult...they have unique and attractive solutions for rectifying weird or unusual problems.

I agree anice simple one on the opposite wall

It looks to me that the entire staircase is not up to code. It's a mishmash. The risers are of different heights, and the treads are of different depths. I don't know how why your home inspector didn't point that out to you before you purchased. My suggestion is to get the stairway fixed...I know, it is a big undertaking, but should someone fall on the stairs, I see a law suit pending. No DIY fix will make it safe.