Can this plugin support adding oxide.usergroup add <name><group> for them to be able to redeem a kit through /kit?

yes it works just need to do like this:

"Commands to execute when player is verified (use {0} for the player's steamid)": [
"oxide.usergroup add {0} groupname",
"inventory.giveto {0} item.shortname",
"inventory.giveto {0} item.shortname"
],

on that example you may give direct items and also grant oxide.group, you may also provide a direct kit.
already test so it works perfect!

got it to work thanks muchos!