The Shark Jack w/v1.1.0 firmaware is running OpenWRT 18.06-SNAPSHOT r0+7850-fb83a51832 according to /etc/openwrt_release, which is "Old Release". The package list is here, and the SJ should be able to handle anything there is a mipsel_24kc family package for. The Hak5 repository would be for the few Hak5 specific tools, like LED, BATTERY, etc. so we really aren't missing much. Just comment out the second line in /etc/opkg/customfeeds.conf like @StrangePanda said and fuggedaboutit.
Make sure to download latest from HAK5 repository, as it has a change to make it work w/firmware 1.1.0.