About as close as Eriksen was today (and closer than Romero was when proximity was claimed to be the reason why it wasn't given). But like I said, arm above head is specifically mentioned as "rarely natural" in terms of body position. You can also see from the images posted that in the short time that the ball travels from the header the arm goes from shoulder-height to above head height, so there's a movement towards the ball too.
For me, the Grealish pen is a stonewall pen under the current guidelines (arm above head). You can argue about the guidelines being dumb, but they're in place and in that context it's an obvious pen. But it's telling that in the collective consciousness (you're not the only one), it's seen as a controversial call whereas another pen that's just as obvious for the same reason according to the guidelines (arm above head) is totally the right decision according to everyone.
And now we're seeing it again with all the pundits claiming that the Romero one is not a penalty due to proximity, and then in the same breath you get people (at least on Swedish TV) saying that the Eriksen one is the correct decision despite the proximity factor and the arm not being elevated. You can even see Kim behind Eriksen with his arm in a similar position as he's running/turning towards the ball. What are the odds that two players in the same image would simultaneously take up unnatural arm positions? Could it actually be that the arm is "justifiable by, the player’s body movement for that specific situation" (using the rule book's wording here)?
Grealish is backpeddling, trying to jump and turn at the same time, completely understandable how it ends up there. Incredibly harsh interpretation to give pens for these things, expecting players to have the body control of a ballet dancer and full awareness of where their arms are at all times. You don't want players doing the old John Terry arms wide while blocking a shot routine but the punishment is not fitting.
