I shot my opponent’s Evra, Halcyon Witness with a Justice Strike, but they did not gain any life from the damage dealt by the creature.
I then tested Justice Strike on a 2/3 Darkblade Agent, and it did not die. This is currently working as intended, as the MTGPQ rules for deathtouch state that it only triggers ‘when this creature deals combat damage to another creature’. However, I would point out that this is different to paper MTG rules.
I was going to test Inner Struggle to see if the same happened, but then I saw that the wording on Inner Struggle is different; in that case the spell deals damage to the creature, and not the creature itself.