I have both Kala and Makala Sopranos and their nut widths are 35mm or 1&3/8” - some other major brands are even narrower. On the Kala I replaced the nut and spaced the strings to 30mm centres, a definite improvement but having played for several years now the slightly closer spaced strings on the Makala are less of an issue than they once were.
(Edit. I think that that is most likely down to a combination of improved technique, familiarity and changes in my fingers. The skin on the end of your finger tips gets tougher as you play and so the fingers interact differently with the Uke.)
IMHO players with bigger fingers should avoid narrow spaced strings ‘cause, in my experience, they are an impediment to playing well.
Barring strings presents it’s own issues but, depending on your finger size and strength, a wide neck might possibly make the task more difficult. What’s much more important though, I believe, is how well the action is set-up and where the fleshy parts of your figures fall on the strings.
I agree, Sopranos can be small slippery things to hold. Once I learned to cheat by using a strap (lower bout to headstock) they became just perfect for much of my playing.