So I thought why not just knit in a new foot instead of trying to repair those unreasonably big holes. I set out on a mission trying to find yarn that would match, turned out to not be easy, but thankfully my mom had some leftover in her stash that ought to be able to the job perfectly.
Here's a picture of the repaired socks, you of see a slight colour and texture change between shaft and foot.
In hindsight I was thinking that it could also have been really cool if I had used a contrast colour instead of trying to match the existing shaft.
I wish I could do this more often. I wear a lot of panties, and the softer the material/wool, the faster the holes develop. I always try to mend them, but there is only south you can do. But the panties are too thin, no way I could knit in new feet.