Wire Question

I got to replace some old 1950s black woven romex that has no ground and only 2 conductors. The cable is in good shape but goes back to a rather gross splice job (wire nut boogey in a crawl space and from the splice further upstream it goes into a J-box that has modern 12/2 with a ground. Why whomever it was just didnt run a new line is beyond me but these are the potential solutions Ive come up with. The circuit goes like this Panel->12/2 J-Box -> 12/2 J-Box branch, split 1: Fan, Lights, GFCI Outlet, 2 Gang Plug Recepticle. Split 2: Closet Lights.

1. I run a seperate ground wire along the grossly spliced romex back to the J-Box to fulfill the ground wire thats missing. This would be stranded wire with crimped ferrule lugs that give it a solid point for use in wire nuts or wago's. This would keep from opening the wall as I could use a fish tape to pull the wire through the outlet box and grab it where it goes into the basement to crawlspace. I cant pull the old romex out without opening the wall, its fixed into locations on a stud.

2. I dead end the old romex, push what I can back into the wall. Remove it from the J-Box and instead run new romex by drilling a hole directly under the 2 Gang Outlet box and use its run 12/2 as the new feed, pigtail wagos and pigtail the GFCI, Lights and Fan to the repurposed feed. Minimum intrusion into the wall.

3. Do bathroom wall renovation early. Going riverwood panel so it would cover the holes I need to make in the wall to remove the tie-downs to pull the old romex out, run the new line and be done with it. Least ghetto option but the most expensive.

The old romex does have a GFCI thats protecting the 2 gang plug recepticle. I just converted two switch/plug combos to a dual switch and seperate gfci and discovered the nasty surprise in the wall. Would this be good until I can do the wall reno this early summer?

Last question. The recepticle is a literal rats nest of copper wire vomit, 3 lines + 1 feeder going into a small 2 gang box Could I instead use stranded wire + wago to help everything fit more nicely? Or should I put a larger box in during wall reno to accomodate everything?