I ordered the capture card and the converter cable, and they should be here on Sunday. I'll try it and see how that goes before looking into any other options.Keen to hear how well it works. Including which Android app to use - there are a few in the in Google Play and some appear to show ads.
So it worked quite well, with negligible perceived lag!
The cable connection- the HDMI from the Pi is at the bottom, then the capture card, then the adapter (used micro usb as that's what my old Samsung tablet has)
So when I first connected it, it asked if I wanted to open the app, and had a tick for always perform this action, which I did not tick. After that, a dialog warning to safely disconnect came up. I went ahead and connected- bad choice. As soon as I connected, I couldn't click the dialog as its over the display area. I had to reboot and try again, clicking the dialog before I connected the Pi. It comes up not in full screen, but if you tap the display, it expands. Tap it again to unexpand.
The Pi fullscreen.
A closer view of the screen.
I used USB Camera Pro - Connect EasyCap or USB WebCam (https://play.google....p;hl=en_US&gl=US
). They have a free version with ads, but with the refund policy on the play store, I figured I'd just go with the regular one, see if it worked, and if so keep it. Better than even starting out with ads as it was only $5.49US.
micro usb to HDMI - https://smile.amazon.../product/B00LN3LQKQ/
capture card - https://smile.amazon.../product/B08CH9FC22/
usb-c to HDMI - https://smile.amazon.../product/B072V9CNTK/
The capture card appears to be out of stock right now
This looks like the same one - https://smile.amazon.com/dp/B08CXMLZCY/
. It's about $5USD more than I paid though.