That Bruno, Son, and Salah comparison is such a weird one. Does it take into account how many penalties each scored, especially Bruno? The average person would probably rate Son and Salah as similar level goal scorers, both being pacey, technical wide forwards, and Bruno behind them. The statistics will likely back that up.
I'm comparing goals a player has scored vs the total the team plays for has scored, to compare a player playing for a team that scores less vs one that scores a lot. You're instead for some reason trying to compare Werner, Lewandowski and Messi which has no relevance to the comparison I'm making.
The simple question to ask really is would Grealish score the same amount of goals as Sancho did, if he played for Dortmund? The answer is yes, especially if you watch the quality of the goals Sancho scored this season in the league. I mean come on, they score almost double the goals in the league Villa do, and that's in 4 less games. It's not a surprise that one scores more than the other.
I get the feeling though no matter what I say you'll just come back with some other obscure point, your mind is set on Sancho, fair enough. But there's a reason why Grealish is preferred to Sancho in the England set up, Sancho's played 20 games and in how many of them has he done anything? Whereas Grealish has played 10 times and been pretty much the best player every time he's played. There's a lot of statistical noise with teams and different leagues but the England setup is the closest we can come to compare the two players on an even playing field.
I know the comparison you're making. I'm saying it just doesn't work in football, especially when dealing with a small sample size. I brought up Werner, Lewandowski and Messi because Werner scored a higher percentage of his teams goals than Lewandowski did in 19/20 for Leipzig. And besides, if you are doing a market share % (which people use for American football a lot - with more relevance), you have to do it with a percentage of minutes played. Both Grealish and Sancho missed gametime this season, a significant amount of it, but I have no idea nor do I feel like putting in the effort of finding what percentage of goals he scored compared to the amount of team goals that were scored while he was on the pitch.
And the answer is no! Grealish isn't a goalscorer, he never has been. He wasn't wasn't Villa played in the championship and he hasn't been in the premier league. What if a team scores 20 goals all season and they have a player score 5 goals? 25% market share. Are they some excellent goalscorer that you can extrapolate out to 20 goals a season if a better team scored 80? Of course not. What are you going on about the quality of goals Sancho scores? Sancho gets in goalscoring positions more often than Grealish does. Grealish rarely gets into goalscoring positions, and he doesn't score many goals. Extrapolating someone's goal totals who scores <10 goals in all competitions every season to someone who is in the 15-20 goal mark in all competitions every season just because a team scores more goals is frankly nonsense and not how football works.
Sancho vs Grealish for England... well Sancho has played more minutes for England anyway, despite being 5 years younger. Sancho actually has a better goal/assist to minute ratio than any of Sterling, Rashford, Grealish, Foden or Saka (stat was before today's game but it would still apply). Sancho, Grealish and Rashford are all on the bench because Southgate wants wingers who are good defensively. Sancho, Grealish and Rashford are all wank at that. Southgate also doesn't rate the Bundesliga, and clearly doesn't rate lower premier league clubs otherwise Grealish would have more minutes as well.
Anyway, Grealish is a terrific footballer in his own right. I prefer Sancho due to being 5 years younger and being equally adept on either wing, while Grealish can only play on the left or as a 10, which are arguably the 2 positions we need less than any. My argument is that Sancho is just a much better goalscorer, as he has a good chunk more goals in his career in more than 100 fewer career games, despite Grealish playing the majority of his games in a much easier league and being 5 years older than the one Sancho has torn up since 18. Sancho takes better shots per game and just gets in more goalscoring chances per game. They're both playmakers - but Sancho has goals to his game and it's something that Grealish just doesn't get all that involved in. Their per 90 stats with dribbling and passing and touches in the box are all similar, just their xG and shot selection are markedly different.