Googled Midi, and found this https://www.amazon.com/Casio-MIDI-Cable-Musical-Keyboards/dp/B00006343G
Looks like that is the one. Never had a keyboard so not a clue where this came from. Guess I can add it to the safe to get rid of pile. Thanks. Solved!
Yes. The cheap ones are DVI-to-HDMI, HDMI-to-DVI isn't as usual and cost a little more. You can also do DisplayPort-to-Anything including VGA.
I've been happy with these cables for both Lightning and Micro USB, plus they're cheap to buy in bulk: https://www.aliexpress.com/item/CAFELE-100-150cm-2-in-1-retractable-USB-fast-charging-Cable-8-pin-For-iPhone-5s/32778220798.html
You can then use these corded USB-C adaptors to make them into a cable that does everything: https://www.amazon.co.uk/dp/B0716QQZZH/ref=sr_1_1?th=1
I went through a few dvi adapters, but these finally did the trick for my 2017 MBP
USB C TO DVI Adapter,Belinda USB 3.1 Type C (USB-C) to DVI Adapter With Aluminium Case for 2017 MacBook Pro/Samsung Galaxy S8 https://www.amazon.com/dp/B073S81DK5/ref=cm_sw_r_cp_tai_YU4HAbYYDYHAC
OK I got this adapter. But I'm not sure it's working correctly as Windows kind of detects it but the PSVR display keeps giving showing the little HDMI logo with the X next to it (assuming it means it's not detected). So i either ordered the wrong adapter or it's defective. I will have to try to find another HDMI monitor to test.