Nothing. In most cases these days the utilities in uboot-tools are only needed for advanced use.
OK, but with the currently distributed version (branched 2023-03-31 / u-boot 2023.04-rc4) I still get the message
Hit any key to stop autoboot: 0 ## Error: "distro_bootcmd" not definded
if I remember correctly and didn’t mess my notes and testing procedures.
Will that get fixed with / before F38 release?
That is fixed with the rc5 build that's in updates-testing, you need to have uboot-images-armv8-2023.04-0.4.rc5.fc38, you're testing with rc4.