Okay - this approach (using the Suru template and exporting from there, for the most faithful recreation of the eventual output) gives this look for the launcher:
Recreating it through the Suru template means the standard highlight is too bright, IMO. This is because a background this dark is unusual for Suru. So we could perhaps make the highlight more subtle for just this one icon?
Or would people prefer to keep the bright highlight, because it makes the squircle more defined on the dark launcher?
The colour stands out a bit compared to the rest of the (Suru) colours, but I guess that’s permissible for such a famous third party app?
Note: the colour going a bit naff on the Firefox itself is a result of the upload, it looks like a normal Firefox logo on my computer