alt Hacker NewsThat's not $20 to compete with a Pi 4, that's $20 for the bare chip. You have to buy all the supporting hardware on top of that. Hobbyists want to avoid routing LPDDR like the plague. There's also the inconvenient fact that digikey shows "0 In Stock", so this listing is just that, something you can't get your hands on as a hobbyist.
$13.24 each if you buy 2000 of them. I remember the lead time being shorter than the 8th of December last time I checked, so I assume they're selling.
I think the biggest impact to hobbyists will be cheaper clone boards made with this chip.