Shame Framework doesn’t sell Blank RGB keyboard. I understand that you won’t see any RGB by default, but then there are places which laser engrave the keyboard, and with a blank one you can theoretically engrave any SVG onto the keyboard making it fully custom.
You can see the result of such a laser engraving in this post.
If you can transform RGB US English layout into Belgian with laser engraving - then that’s it.
Not sure how present such services are in Europe, but I found one in Germany pretty quickly.