GIMP Version: 2.8 - 2.10
Operating System: Windows
GIMP Experience: Intermediate Level

List any relevant plug-ins or scripts:
G'MIC

---

Struggling to make G'MIC plug-in working with GIMP Portable.(both 2.8 and 2.10).
Even following several instructions found around the web, the plug-in is not added to GIMP menu

Has anybody been more lucky (skilled)?

2.8 portable, sheesh! Maybe you're trying to install too recent version?
Last version for 2.8 is 2.96
If you're intermediate I don't need to tell you how and where to install plug-ins...

Well there's one more thing, I've never installed G'MIC using the installer, always use the .zip be it normal Gimp or portable.
With portable (wondering which of the dozen portables you have?) I think .zip is the only way to go.

https://gmic.eu/files/windows/

First thing, are these portables from portableapps.com ? There are others - samj for example.
Next, until comparatively recently GimpPortable was 32 bit and there were very few gimp_gmic_qt 32 bit plugins. see: https://gmic.eu/files/windows/32bits_(old)/ (stupid underscore use https://tinyurl.com/5n76szz3 ) and get the zip. For the last portable 2.10.38 there are problems with file versions. I went back to version 3.4.0 from https://gmic.eu/files/windows/ Work you way through versions if you want.

GIMPPortable for some reason does not make a full user profile for plug-ins ...Data\.gimp\plug-ins and it is better to get the gimp_gmic zip version and just add to the portable version. How robust to moving about from computer-to-computer this is, I do not know. Win11 screenshots.



Then you need to add the path in Edit -> Preferences -> Files -> Plug-ins



...and that is working, at least it is here



best of luck with old stuff.

No way.
Even with the welcome advices, here still having hard time trying to convince G'MIC to show up in the GIMP Filter menu.

Portable versions are 2.8.6 and 2.10 from PortableApps (preference against newer versions is not passion for vintage, but separate lateral panels that can be sent to second monitor in extended desktop mode that allow full drawing window on primary screen) and G'MIC is in the zip version (as you also suggested) and fresh new copy also downloaded from the https://gmic.eu/files/windows/32bits_(old)/ link suggested by rich2005.

Unzipped the:
https://gmic.eu/files/windows/32bits_(old)/gmic_gimp2.8_qt_win32.zip
https://gmic.eu/files/windows/32bits_(old)/gmic_gimp2.10_qt_win32.zip
archives and copied the gmic_gimp_qt whole folder inside the GIMP_Portable/gimp/lib/gimp/2.0/plug-ins/ directory of corresponding GIMP_Portable version (both 2,8 and 2,10)
Updated the Edit -> Preferences -> Files -> Plug-ins to also include GIMP_Portable/gimp/lib/gimp/2.0/plug-ins/gmic_gimp_qt/
Restarted GIMP and created a new empty image...
... nothing happened for both GIMP_Portables.

Is there anything I'm still missing?
(before definitively givin' up)

Not surprised, try and follow the screenshots.

(1) Put the unzipped gmic folder in the GIMPPortable folder not the plugins folder.
(2) Add that location to the paths in Edit -> Preferences -> Folders -> Plug-ins (for each GIMPPortable version)
(3) When it comes to Gimp 2.10, Windows gimp_gmic_qt tended to evolve with Gimp version. Starting with GIMPPortable 2.10.14 it is 64 bit, so get a 64 bit gmic for Gimp 2.10.38 The version does matter , newer or older gmic versions incompatible. This one worked for me , with GIMPPortable 2.10.38 https://gmic.eu/files/windows/gmic_3.4.0_qt_win64.zip Some slightly older (or a little newer) might also work.

Latest version of gmic is not showing in gimp 2.10. I also tested this.