tl;dr: Definitely accurate in message, less accurate in details.
Since I don't get my news from memes:
The man's name is Kenneth Vinyard. The incident occurred in Monaca, PA, on November 6, 2022. The gunshot victim, Rashaun Smith, was airlifted, but ultimately died. The shooter, Yeshua Bratcher, was charged with (among other things) homicide. As of January 2023, Bratcher was scheduled to go to trial in May 2023, but that's all I can find about that.
Vinyard was in the vicinity of a gunshot victim when the off-duty Center Township (just minutes from Monaca) police officer John Hawk did indeed push Vinyard to the ground, and Vinyard did indeed die. There is cell phone video of all this, but I haven't found it yet.
I said "vicinity of a gunshot victim" because different articles describe Vinyard as "rushing to the victim's side" and "rendering aid", or approaching on-duty, uniformed police near the crime scene to offer evidence. The two scenarios seem mutually exclusive, but because the latter description is what the AG ultimately based their charges against Hawk on in late 2023, I tend to believe that.
In May 2023, the Beaver County coroner ruled Vinyard's death an accident, saying that the cause of death was "was hypertensive and atherosclerotic disease and said, 'blunt force trauma of the head and associated stress that occurred during the confrontation contributed to his demise.'" In the same month, a lawsuit by Vinyard's family against Center Township was settled for $950K.
The article just linked seems to contain the most cogent description of events on November 6, 2022, in Monaca:
The Pennsylvania Attorney General's Office said Vinyard, 48, approached an officer who responded to a shooting scene to offer potential evidence he wanted to provide to police. The AG's office said Hawk, an off-duty Center Township Police Department officer in casual clothes, confronted Vinyard and "pulled him away from the officer."
The AG's office alleged that a short time later, Hawk struck the victim in the chest — while performing a leg-sweep maneuver — which knocked the Vinyard to the ground.
Vinyard was later pronounced dead at a hospital. A medical examiner concluded that the blunt-force trauma and accompanying stress contributed to Vinyard's death.
The AG's office also said that Hawk did not announce himself as a police officer and was not heard or seen announcing Vinyard under arrest. Hawk also did not have the authority at the time to arrest Vinyard, according to the AG's office.
Anyway - there's a ton of articles out there if you want to dig deeper on this case.