Fpcupdeluxe will perform an isolated install of FPC (and Lazarus).
It uses its own fpc.cfg, located in the install-directory.
And tries to make it work on as many systems as possible.
The global fpc.cfg will not be used, to prevent issues between different installs.
As maintainer, I have limited resources to test. At the moment, I use a VM (on Win10) with OSX 10.14 to test the functionality of fpcupdeluxe.
Besides, I always advice to use the official sources, binaries, installers when available !
And use fpcupdeluxe only for special demands.
The fpcupdeluxe binaries themselves are all made on a Win10-system by cross-compiling.
I am very interested and eager for any advice that can make fpcupdeluxe better !