I have been using XAMPP for a few years
I like to keep things simple and only use PHP (no Maria/SQL, Perl, etc)
I am also not an installer
I have created XAP: XAMPP with PHP only
XAMPP (7.2.30) portable is a 72MB 7z extracting 12,887 files to 580MB
XAP is a 6MB rar extracting 168 files to 19MB
XAP is designed simply to allow php scripts to run in a browser. There are no other features and no control panel
All paths are relative so I simply extract XAP to any location and it will run without any configuration changes required
If anyone else might find this useful, I'm happy to post the XAMPP to XAP conversion instructions here