Perspective session switch and pass login credentials across gateways

So I have a user management project that needs to be able to switch between gateways. I got it to switch gateways but the credentials don’t transfer over to the new app. Is there a way to try and validate a currently logged in user on a different gateway? Also when you switch on the perspective app it kicks you to your default browser which isn’t a big deal but annoying to deal with.
edit: Reworded to clarify

I know its been a long time, but did you have any success with this? I'm looking to do the exact same thing.

No, our IdP isn't set up to handle this, nor is switching users seamlessly across gateways likely to happen anytime soon.

Your best bet is probably an external IdP, though it may or may not still distinguish between the two different applications and require the additional sign in.