Any VPN that can work on application basis?

Say App1 can only be accessed by Server1 and app2 by server2.

If someone wants to use both the apps, is there a solution where I can activate VPN (individually) and to only these two apps?

So rest of the PC apps work normally.

Is there any solution, open source or otherwise that has such/similar implementation?

PS :: I am aware it is possible with stunnel to have multiple connections but these apps work by VPN only.. Just tunneling not enough as they are too complex.