I did try the new TMS FMX UI Pack v3.7.0.0 on my multiplatform FMX project (Windows, macOS, Linux64) under 10.3 Rio.
I can't compile the FMX.TMSPersistence.pas for the Linux platform:
[DCC Error] FMX.TMSPersistence.pas(349): E2250 There is no overloaded version of 'GetString' that can be called with these arguments
After it I modified the FMX.TMSUtils.pas temporarily:
function GetShortStringString(const ShortStringPointer: PSymbolName): string;
begin
{$IFDEF FMXLIB}
{$IFDEF LINUX}
// Result := TEncoding.UTF8.GetString(ShortStringPointer^); //it does not work
Result := string(ShortStringPointer^); //it does work
{$ELSE}
Result := string(ShortStringPointer^);
{$ENDIF}
{$ELSE}
Result := string(ShortStringPointer^);
{$ENDIF}
end;