'Ping!' is the one-note electronic sound that phones, computers and other electronic devices make. For example, some people say "I'll ping you an email" or "I'll ping you a message/a quote etc", meaning that you'll send it electronically. When you receive it, the device might make a 'Ping!' sound.
Here's a guess at what your sentence means:
In normal times, you'd invite your friends to come to your house for a party, and they would offer to bring food and drink. The normal thing to say would be "I'll make a cake to bring along".
At the moment, the world is a very different place. We 'meet' our friends via Zoom or Google Hangouts. If you arrange a virtual get-together with friends, someone - as a joke - might say "I'll make a cake to ping along". It's an acknowledgement of the fact that we're doing our best to carry on as normal in very unusual times.