I like the result of applying (mainly to portraits) the PS plug-in from RedPawMedia called Beautifier.
Question: is there a G'MIC plug-in which performs as that one?
If yes: which one and which are the best setting for the parameters to get almost identical results?
If not: (question becomes a challenge) would some great G'MIC writer be willing to provide one?
Many thanks in advance

Have you tried Beautify ?
It does have a skin filter included.

I thought that too Graechan. I have had it for over a year now and never use it.

Yes, Beautify is very rich in possibilities, but I didn't find one close to RPM Beautifier (certainly my fault)

IMO it should not be used simply directly on the image and "that's it" (this way it's fine only in rare cases).
Normally I use it on a duplicated layer, then I "overlay" it on the base (untouched) one. Depending on the luminosity of the original picture you can also use multiply, playing with opacity.
Well, anyhow it's a matter of taste

Are you still learning G'MIC? Maybe this would be a good thing to try

Have a look at, virtualPhotographer PS plugin.

Yes, GC, I'm still on that "battlefield"...so, you are right, why not to try?
I put this post here because I'm a bit..lazy, so I hoped to find someone who creates a first brilliant G'mic solution, upon which I can later play with personal extensions.
(for instance, I took the excellent "FadeMirror" kindly created for me by David and derived a "WaterReflect" command, which I now also use on my pictures; when the image is primarily vertical I use FadeMirror, when is very much extended horizontally, I use WaterReflect....in both cases the goal is to have a nice full screen-size image to look at).
Let's see...

Yes, Odinbc, I have it; here I was just asking for a "gimp" solution...

making a (partial) scanning of the many available G'MIC filters, I guess I found the one I looked for: Portrait Retouching
I'll play with it ...

yes, G'MIC Portrait Retouching is definitely the right one to use
thanks to the author!