minicap is another adb application that will provide a video stream from the an android device. There is another thread here somewhere about people experimenting with it but it never really developed past that. Even with that though you would need to root your android device and disable the secured video sources flag using something like xposed to get content from netflix (it will output a black box). I would have started with that but getting it running looks like a real PITA.
That device you linked to certainly looks promising. That is about the ceiling of what I would be willing to spend to get this working again. I'll take a look for something similar!
I did notice this on the HDfury site: https://www.hdfury.com/product/splitter-4k-uhdpro/ which is a splitter that describes an integrated scaler:
Splitter 4K UHD/PRO is a 2-Port DVI/HDMI splitter with integrated HDCP decryption/encryption engines, channel independant scaling engine and is compliant with HDMI Rev 1.4 and HDCP Rev 1.3 specifications.
Splitter 4K UHD/PRO receives DVI/HDMI inputs, process HDCP decryption and encryption, scale up/down one or both channel and transmits the data to 2 DVI/HDMI ports.
EDIT: ah nevermind, didn't notice it caps out at 30hz
If that is the case, that device is $100 and has a splitter already integrated. I think I'll contact them and ask about it, will report back anything I learn!