This is a GIMP script that aligns the specified layer(s) against the specified image or another layer. Alignment is performed horizontally (none, left, center, right) and/or vertically (none, top, ...
On modern Linux, GIMP 2.10's Python-Fu is effectively gone — gimp-python was dropped because it depended on Python 2 (EOL), so a Python plugin won't install. But Script-Fu (Scheme) is always built in, ...