Skinner and Swayman are extremely alike in their profiles as goaltenders. Both goalies are 25 years old, and Swayman has only played 9 more games than Skinner. Swayman's save percentage is 9 points higher and he has only 7 more wins than Skinner. However, Skinner has taken his team to the Stanley Cup Final and will be significantly more experienced when he signs his next deal than Swayman is now.
While Swayman to this point has been a little better than Stuart Skinner, they're directly comparable, and will likely earn a relatively similar salary. If Skinner excels over the next two seasons and perhaps adds a Stanley Cup with the Oilers, he'll have grounds to perhaps demand more salary than Swayman. The salary cap is increasing as well, which will give the Oilers some space to sign Skinner, but it also gives him more grounds to demand higher salary.
Swayman has certainly set the market for younger, more inexperienced starting goalies. After Stuart Skinner joined a new agent literally representing a goalie union, they'll certainly be using Swayman as a direct comparable. The Oilers will need to clear some significant cap space to give Skinner a $6M raise in 2 years.