Serviio

I would like to be able to specify the presentation category order.

E g I'd really like to see the order

Series
Movies
Folders
...

but Serviio always sends the menue of categories in alphabetical order.

Actually, that's your player that is doing that, not Serviio. When I look at the presentation list in MediaBrowser (which provides the native order) I see them listed as Titles, Movies, Series, Folders, Last Added, and Playlist. But when I use Kodi on my Shield players, they are listed alphabetical as you mentioned. However, my Roku devices all show it in the same order as MediaBrowser, so it is possible for the player to show them in the order given by Serviio.

All that said, you cannot alter the order in the Serviio console to rearrange the presentation order. I could see a benefit of having such a function, but as I mentioned some players will ignore the order and sort them the way they want, regardless of what Serviio is providing.