I tried installing InstallAware X17. Took a look then uninstalled it, I think I'll stick with Inno Setup Compiler.
AFAIK X17 is Windows-only and is not free, but Multi Platform is free for open source projects and supports macOS and Linux, too.
The former ought to be built with Delphi and the latter with Lazarus.
So this is how they're able to basically compile existing X17 projects (even from 20 years ago!) literally intact (with custom UIs and everything) for Mac and Linux, pretty incredible technical feat (that could only be made possible by Lazarus!)
