It was a speedball, Wendy said so in the next episode when she went to talk to Tara about it.

lol, writing from the future here (I have been rewatching the series on Prime). You were so correct in your vision!

Writing from the future to say that The Homeless Lady was a ghost/angel of sorts. But since you have seen the finale by now I assume, you may have figured this out.

Exactly. I was surprised nobody else had picked up on this.

Writing from the future to say that Primo was going to simply take the gun away at first, then said, "Screw it, move over." He was going to take off with Darvaney, that's why he got popped.