Experimenting with making different sizes of these slippers.
These ones end up to be 26cm long which is size 42 Euro.
I think I could add a stitch or two extra width but they do stretch.
They are 28 rows of the main colour, then another 6 of the contrast for the toe.
I joined 13 rows along the foot, which left 15 rows for each side of the ankle opening.
I made 4 rows of the edging around the ankle.
I tried one on my husbands foot and it fit.

I made a second pair in a medium size. It turned out about 25cm long.
26 rows of main colour before the toe. Kept to six rows for the toe which I joined as normal.
12 rows of main colour joined for the foot, before the ankle.
14 rows open for ankle.

I plan to make another pair in small size.