there is a udev rule /etc/udev/rules.d/83-wpan0-start-lowpan0.rules that start lowpan.service, which is located : /lib/systemd/system/lowpan.service
That calls /usr/sbin/create_lowpan, which wants some arguments. The same lowpan.service has a field called EnvironmentFile, which supplies the values of the arguments to create_lowpan. It is this create_lowpan that should make your devices show up in ifconfig.
But I’m not sure why that doesn’t load for you automatically, if you’ve successfully programmed the cc1352 and are not loading the overlay to disable bcfserial. Your output seems to confirm that these are both the case.
I’ve been able to get lowpan0 and wpan1 to show up using the 3-23-23 flasher build. I’m pretty sure it was working in my factory image before I broke my image elsewhere, so I don’t think it has anything to do with the build date, as long as its an emmc flasher image. I found that the sd card images definitely don’t work for wpan, as confirmed here Beagleplay - lowpan0/wpan1 only show up when running from emmc - #2 by RobertCNelson