For those who dont want to solder, theres a module for this:
<a href="https://auvidea.eu/product/70501/" rel="nofollow">https://auvidea.eu/product/70501/</a><p>Mouser:
<a href="https://www.mouser.com/ProductDetail/Auvidea/70501?qs=EU6FO9ffTwcl%252BA7ajZcePA%3D%3D&gclid=EAIaIQobChMI5uj835it6wIVtx-tBh1-UgetEAQYASABEgLF4_D_BwE" rel="nofollow">https://www.mouser.com/ProductDetail/Auvidea/70501?qs=EU6FO9...</a><p>Datasheet:
<a href="https://www.mouser.com/datasheet/2/864/B10x_technical_reference_1.4-1130369.pdf" rel="nofollow">https://www.mouser.com/datasheet/2/864/B10x_technical_refere...</a><p>Edit: Theres also this one on Amazon: <a href="https://www.amazon.com/gp/product/B0899L6ZXZ/" rel="nofollow">https://www.amazon.com/gp/product/B0899L6ZXZ/</a>
Slightly off-topic, but I've been wanting an HDMI Freeze button for a while.<p>I looked at the auvidea link that kayfox suggested, and could probably implement it in software on an RPi. But that has limited resolution and frame rate (25 fps).<p>For a feature built into most projectors, I'm surprised there's no products to do this.