I bought this cheap (under 20e) HDMI capture device, and it seems to work with my MorphOS setup. Image quality isn't perfect and seems to have some sharpening which makes it look a bit different than it should be, but seems to work in various resolutions and it's still quite ok. It can also be that I just can't use grabbing software (OBS) well enough yet... Here are some videos I've made so far.