The DSA is the part that applies to all companies in some way as well (things like the need for moderation and a way for people to reach you with complaints). The DMA is about the market and how to deal with monopolies.
Search for "laptop" here: https://en.wikipedia.org/wiki/Coaxial_power_connector#Listin...
Same for all the smaller dedicated devices (audio recorders, camera, controllers etc.)
Those didn't go the barrel plug route in the first place to allow for charging through the same port, and would have been a loophole if barrel was mandated. USB-C was honestly the only option that made sense IMHO.
Most of those used either USB or a barrel plug depending on their size.
raspberry pi, e-readers
USB.
Same for all the smaller dedicated devices (audio recorders, camera, controllers etc.)
Many of those use smaller barrel plugs, appropriate for their lower voltage.
The main problem with USB-C is the tiny fragile connector (search for images of "bent USB-C"), and the fact that it's a standard that tries to be what should really be a bunch of separate standards. It's hard to get a barrel plug wrong. It's too easy to get USB-C wrong, and cause damaged devices:
Besides, apple are one of the decision makers in the usb c standard, the legislation mandated a standard, but not a specific one, just the same one for all, and this forum which includes apple decided to go with usb c https://www.usb.org/members