Digging holes to concrete fence posts

here also very compact, rocky and clayey:

a very good welded hand earth auger (mws disassemblable garden auger / planting auger ) DN 200 with an extension of 500mm has proven itself excellently to me and seems like a purchase for life. So far used for planting holes for hedges and trees as well as point foundations for garden houses, fences, and pull-up bars. It is quiet, but still exhausting ;) But you can get about a meter deep if you don't hit rock and can clear the hole even with a small cross-section superbly and back-friendly. If the foundation should become larger, maybe two holes, or simply go over it again with a spade. That works noticeably easier with an existing hole in the middle!

Much better than any toy for a power drill!

I think that will be difficult. Even the simplest motorized earth drill comes with different requirements than an SDS attachment for, for example, a rotary hammer. This starts with the size of the drilling device, the operation while standing, the weight (>10kg), and also the power (entry-level class 3HP gasoline engine, >2kW power).

Just take a look at what they have for rental equipment at the local hardware store. Here, you can get almost everything from the floor sander to the concrete mixer to the motor plow.

Hand auger with long lever, the walls stay intact and one can set the anchors directly with earth-moist (ready-mixed) concrete, one bag per hole and it lasts forever

I’ll buy myself a hand drill. And see what I can borrow at the hardware store. I just don’t want to break anything borrowed because of the rocky ground.

I will then concrete in these sleeves. And should one still dig a hole up to 80cm deep?