Turkey supported Georgians and Ukraine's NATO application in 2008 (whilst European powers like Germany, France, Italy and co opposed it). Same with NATO applications with countries like N. Macedonia and others.

Turkey isn't trying to "keep both masters happy" because they don't have to. They do what's best in their national interest and security. If Sweden follows up on their promises, they will join. If not, they won't and Erdogan is the only politician in Turkey who would be ready to make such deal with Sweden.