Solution to both (replace # with your client and site numbers):
cp /lib/x86_64-linux-gnu/libnss_* /var/www/clients/client#/web#/lib/x86_64-linux-gnu/
So what to do if I don't have /lib/x86_64-linux-gnu/libnss_* or /lib/x86-linux-gnu/libnss_* installed?
Permanent solution likely involves a fix in /etc/jailkit/jk_init.ini. The paths it contains are wrong for some of the libs and it does not list all the necessary libs.
Is this something that will solve itself from upstream by magical fairies or do I need to manually do this (and what exactly)
So for now I use FTPS, but I rather have SFTP working too (needing an ssh account is a plus for me...)