Doing a decent job of them is hard work.
Even knowing how to do it, and prepping ahead, it's still hard work.
It's time consuming, and if you want something decent that won't rot, then it needs care.
It's also rather visceral, and not to everyone's comfort, iimmc ? Texture, smell, etc.,
On t'other hand, it can be a very good demonstration to work on, and you do end up with something useful at the end
Very appropriate for the Crannog
I presume you mean preserved with the hair on ? I managed a red deer one like that once. It was a lovely pelt, but the next one I worked on the hair slipped off, and the mess was not fun. The hide tanned, but the sticky bloodied hair clung to everything.
I was glad to see the back of that one. It ended up the skin on a bodran.
Lots of Youtube videos about I'd expect.
Nicest skins I know though are tanned with mimosa bark, like those at SkyeSkyns.