Is it possible to establish a APNS push notification without a Mac?
On the client side, I use the Phonegap Push Plugin in a Cordova Hybrid App, created with Intel XDK. I see, that in the legacy build options, there are options for APNS, but these builds are deprecated and soon will be removed. In the current build options, there is only an option to upload the overall certificate.
On the server side, I use Loopback.io, together with https://github.com/strongloop/loopback-component-push
Both work perfectly for Android/GCM. But for APNS I need the certificate AND a private key. I don't own a Mac (and have no plans to buy one), so the instructions from Apple and in the web to use the "Mac OS X Keychain" don't help me much.
Do I really have to own a Mac to accomplish this?
You should not need a Mac to do what they are describing. Most of this involves doing operations with the openssl command, which is an open source tool available on all platforms. I can't give you any specific details, but I'm pretty confident you can find some hints on stack overflow and similar forums regarding how to proceed.