Thanks @grb - I will have a look at those - unfortunately I didn’t find them when I first searched although to be fair I didn’t search for ‘jump’ on its own (actually I only recalled the use of the term ‘jump’ when I was writing the above post after unsuccessful searches); I was searching mainly under ‘alphabetical quick access’ and similar - so maybe had been using too long a search query (3+ words), as didn’t even come across the third one you posted! 
An alphabetical jumplist and Could I create a PR for an alphabetical scrollbar on the mobile apps? are exactly what I was referring to - for mobile apps. The latter is interesting in terms of the response/considerations stated from the BW (Dev?) Team and understanding the thinking about change requests. And Jump to location in list? describes exactly what I was referring to for desktop apps (Windows & macOS).
Definitely think this is pretty useful and simple functionality that I’m surprised isn’t already present (not being negative, just genuinely would have thought that it, along with a couple of other things there are FRs for, would have been pretty stock standard (especially in mobile apps) and already present.
