es. Easy with the walls open. Coax is cheap. May as well.

How will you know where to put the Ethernet jacks? The advantage of wi-fi is that networked devices can be used anywhere. And phones, tablets, e-readers and many other devices are never wired. Are you planning to put a (desktop) computer in each room?

If you routed coax, do you know where you'd put a cable box or TV in each room?

I would plan for a space where cable TV or fiber-optic cable would enter the house and where I could put all my network equipment (modem, router, etc.). I have a plywood patch panel in a closet something like this on which I've hung all my networking equipment. Be sure there are outlets nearby. And put lots of outlets around the house too.

-- amateur (uses Sonos and only wi-fi including for TV)

Run one (1) network cable to your ADU in a sleeve and have a router split 4 ways there. Don't fall for CAT7 b.s. garbage and use CAT6, CAT6a, or CAT8.

I would add coax. I'm doing the same with an ADU
 I'm relying on wifi or internet accessfor