I’m not sure how exporting it as a single JSON file would work, or if there’s a tool or method to merge them. (I’m not familiar with Figma, this tool the PatternFly folks built, or tokens.)
I tried merging them, but Penpot complained about the file. It seems to import the colors, but nothing else. I probably did something wrong.
Ok, I manage to create a single set of tokens. The problem was that, in figma, they are using variables, not tokens. So I was able to transform them to Tokens format with Tokens Studio plugin, and I got a (really) big file with a lot of tokens. I can’t guarantee they are ok because the transformation from variables to tokens is not 1:1 but maybe it is useful to play around: