To follow up on my previous post about the GPD Pocket:
Turns out that there in fact is a bluetooth controller in the GPD pocket as pointed out to me on Facebook. But I didn't get it to work yet. It probably requires a proprietary firmware. The device shows up as Broadcom Corp BCM2045A0 in the output of sudo lspci -v.
Sound does work with the default 4.11.0 Fedora kernel. But it does not work with the 4.12.0 rawhide kernel.
I now also got encryption working. The issue was that the grub config had rd.luks.uuid=luks-None. I replaced None by the right UUID (got it from cryptsetup luksUUID /dev/mmcblk0p3). I also did the same in /etc/crypttab. Nonte that after fixing /etc/default/grub and /etc/crypttab you need to regenerate your initrd and grub config.