Nicolas Jackson might have played as a striker for Chelsea but he is also capable of playing on the wing. If I remember correctly Jackson was playing as a winger in his former club before he moved to Chelsea and he was very effective in that role so he can also take on that role for Manchester United if he joins but the question is why are Manchester United trying to do away with Garnacho when he is a very talented player are they going forward are backwards?
Everything depends on the coach's assessment of his players, and each team has a different perspective, including the Manchester United coach, who didn't fit into his desired scenario. Although Garnacho's performance on other teams was considered excellent, every club wants players who can lift their team and comply with the coach's established rules. I think there are many things to consider in this regard.
Liverpool performed well last season and they secured the English Premier League title with a few matches to play last season and they have understood that the Premier League competition will be more difficult for them next season that is why they have added some good quality players to their club this season so that they can ensure victory against the opponents who are difficult in the next season. Manchester City's performance was not good last season and I have not seen them buy any such players in this transfer window so it is expected that they will start the next season with the previous players, now the question is how successful they will be there if they start the new season with the previous players. I think that even if Manchester City cannot do very well, Arsenal will do quite well next season and Arsenal has already taken all the preparations to do well.