Afaik release lazarus is now still 3.0.4 compatible, which doesn't have rtl-generics, a lot of the contents of lazutils is about container types, and some consolidation there seems in order.
Fileutils returns utf8 strings in normal strings, so that is useless for Free Pascal.
A first move would be to start merging small things back. E.g. things like that there now is a uitypes in lazutils, and a system.uitypes in freepascal.
utf8process is also fairly small in 3.2.x+, and basicaly an alias unit.
fileutils seems to have assumptions about utf8 use, and returns utf8 strings in normal string types.