Should work, might depend where Gimp is installed, memory stick, second hdd… A quick check.
PortableApps had problems with Gimp 2.10.2 - looks like Gimp 2.10.4 is better.
For maximum portability it is a 32 bit Gimp so you need the 32 bit gmic_gimp Which is probably your problem. Get the zip file https://gmic.eu/files/windows/gmic_gimp2.10_qt_win32.zip
Look in Edit -> Preferences -> Folders -> Plug-ins for the path to the plugins folder. Should be …\GIMPPortable\Data.gimp\plug-ins screenshot: https://i.imgur.com/V7acXlk.jpg
Unzip gmic_gimp, keep the folder name same as the plugin and put it in that folder. https://i.imgur.com/rsidndg.jpg
Start up Gimp, open an image, check if it works. Does here: https://i.imgur.com/7WPaw6q.jpg