Well shit it worked. I guess I should read up on groups, I was absolutely clueless about that. Thanks a bunch!
EDIT: actually it only works for USB installs, not for the payload injector... I'll try to troubleshoot for a bit
EDIT2: I tried creating a group (the created group worked with USB installs), changing the group, adding the rule described here: nh-server.github io/switch-guide/extras/adding_udev/ and modifying the existing rule with the content described in the link, to no avail. It's no big deal though, I'll just use the usual linux payload injector, and now with the new rule I created I don't have to run that one as root
Check '4. For RCM part' section here: https://github.com/developersu/ns-usbloader#linux
You're welcome %)