Good Day,
I know I can download Bookerly
here , but this is not the same version as on the newest Firmware. The official font in version 1.0.10 contains version 1.0.0 as "LCD" font, version 1.0.2 is the same as in 1.0.10 but with less glyphs.
I do own a Kindle, so I renamed all fonts and compared them on device. The internal font is distinctivly different from the web download