Please put a pointing device on the 500. They make the 400 as tiny as possible, then waste the smallness by making you burn a bunch of desk space by adding a mouse.
The Pi 400 is small because it's meant to be aimed at the young. But young children are good with clicking buttons and poor with fine dexterity; they will likely do better with mice.
A clip-on trackpad to go alongside it would be nice, though.
I'm not really the target market but I am hoping a Pi 500 will tick all the right boxes to use as a cheap computer in a space-constrained workshop.