Hi,
I did this 12 months ago. Although your initial title made me laugh as we had a mini digger in last weekend and buried 200m of electrical cable and water pipe in the back garden.
But to Ethernet… really depends on the construction on the walls and how the house was built… my current property is solid walls so it has been really hard, we had floorboards galore up when renovating and laid a lot of cable, created up and downstairs comms cabinets as well as a switch cabinet in the garage and a Poe switch going out to the shed once the new power is live. Dry lining and it’s hard work but doable with cable rods. Solid walls Really messy and expensive.
I like the suggestion of running some fibre as then you can get a few more ducting options due to the physical media.
Jenny