I experienced this issue several times and I wonder what’s the reason:
For some Google typefaces Figma don’t show all the available styles.
For example:
Reem Kufi
In the Google Fonts website there you see the 4 different styles it has. But in Figma the style selection dropdown is disabled.
The font is not installed on my computer.
It seems to be an issue for a handful of fonts only.
I found those two that have several styles but don’t show up in Figma: