As others mentioned: moonlight streaming or steam link streaming.
A possible alternative is the app Orion from Lux, the makers of the Halide camera app.
As your iPad Pro has USB-C, you can use cheap HDMI - USB-C capture cards with Orion. Checkout this blogpost on how to set it up and which capture cards work https://www.lux.camera/use-your-ipad-as-an-hdmi-monitor-with-orion/
As others mentioned: moonlight streaming or steam link streaming.
A possible alternative is the app Orion from Lux, the makers of the Halide camera app. As your iPad Pro has USB-C, you can use cheap HDMI - USB-C capture cards with Orion. Checkout this blogpost on how to set it up and which capture cards work https://www.lux.camera/use-your-ipad-as-an-hdmi-monitor-with-orion/