I didn't want to publicize it, just in case, to keep the supply available but now that you've done it:
I strongly recommend that product. As a STB manufacturer it is immensely useful. You can keep your 4k DV video output, and use a 10$ USB capture to develop and test as if you had a real TV.
It is also useful to reduce ewaste: there have been some 4k TVs without HDCP2. 2+HDMI 2.0, this makes it 4k again.
Likewise, I have an HDMI 1.4 AVR, this splitter allows me to use it at full feature (DTS-HD being not available in HDMI 1.4)
My only complain is not being able to switch to tunneled Dolby Vision (as a user you probably don't care), and it's not immensely stable (you probably want to give it a proper radiator)
https://www.amazon.com/Splitter-l-b-y-Vision-Atmos-Scaler/dp...
Some folks use that splitter with home theater projectors to enable LLDV (player-led aka Low Latency Dolby Vision).
For more money and functionality, see the devices made by HDFury (mentioned at the end of the article). e.g. the Dr HDMI 4K:
https://hdfury.com/product/dr-hdmi-4k/