I don't think Napoli would say okay to any kind of swap deal. They would rather accept cash for Osimhen and their demand would surely be insane amount of money. Arsenal aren't a poor team in the end. Their financial condition must still be solid despite spending a lot of money in the recent times.
Arsenal does not look like a team for Victor Osimhen, I do not see how the deal will work. This is just another news, maybe to throw other clubs away from the scent of the striker they want to really sign. Gabriel Jesus seems very important for Arsenal, he was able to fill in and play for Saka while he was injured, and he did well. If Arsenal are considering swapping him for another player, they will consider bringing in a player too that can play multiple roles and also fill in Saka's position. Napoli may also not like to sell if they still remain in the champions league till that time.
Arsenal is good club and currently one of the best club in Europe at the moment in terms of performance but I don't think it'll be destination for a player like Victor Osimhen. The Nigeria international is an 18 box striker that always wants the passes and crosses to convert them to goal why Arsenal plays a different kind of football.
Again Arsenal doesn't have issues with the top 9 striking position as they already have players who very good in that position. If Osimhen wants to leave Napoli in January, I think a move to Real Madrid should be a better option for the Nigeria international.