Parse server as proxy for other APIs?

I am thinking of deploying a new app with Parse as backend. For authentication and other stuff.
But there are also a couple of other services (APIs) I need to fetch data from to the app.

What are your thoughts on how I should access these other services?
Should the calls be proxied through Parse or can I use the Parse tokens in my other service for authentication somehow? Can they be validated in these other services somehow?

I did a simple test with a cloud function that acted as a proxy and made the calls to the other backends. It worked but feels like a lot of overhead.