Dortmund are currently looking for a winger. Gnabry and Neymar have been entered as most recent rumours on Transfermarkt. Gnabry is a realistic rumour maybe but I don't think the same about Neymar. Because his salary demand would be huge and he is already making more than 50 million euros per year. Dortmund are paying Haller the biggest amount of salary now which is 11 million euros per year. I don't think Dortmund are interested in any experienced world star transfer now.
Because they don't have the aim of building a squad whose quality is nearly the same as Bayern Munich in the first place.
I think it's true that Dortmund will only spend money to pay Neymar and I think wingers like Neymar are not the era anymore. Dortmund must look for a much younger winger and Sergey Gnabry is actually not a young winger either, but if there is no other choice at least Dortmund can entrust this position to Gnabry for one or two seasons. We know that the relationship between Dortmund and Bayern Munich is very harmonious in matters of player transfers between clubs and that will also make it easier for Dortmund to be able to get Gnabry in the near future.