@arnor: since Dec 2021 Locus can handle ZIPed themes, i.e. just drop the ZIP file into the _themes folder. Done.
Thanks.
Just to be clear because I'm not quite at home in Locus yet.
I have OpenAndroMaps installed. Of course also the corresponding Theme (both V5) Now also the FzOAM theme. Themes are zipped. However, in Locus4, I don't see the FzOAM theme in the themechangescreen. Do I need other maps (eg Freizeitkarte) for the FzOAM theme to use this theme.